WIP: Refactored CSC __getitem__ to use changes in _unpack_index.
WIP: Refactored CSC __getitem__ to use changes in _unpack_index.

This introduces a failing test due to a bug in CSC's .nonzero() where
the indices are not sorted C-style as described here:
http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html#boolean

This addresses @pv comments:
https://github.com/scipy/scipy/pull/2689#discussion-diff-5670362
https://github.com/scipy/scipy/pull/2689#discussion-diff-5670402

trankmichael/scipy,anntzer/scipy,sonnyhu/scipy,jamestwebber/scipy,vhaasteren/scipy,mhogg/scipy,WarrenWeckesser/scipy,Gillu13/scipy,nonhermitian/scipy,grlee77/scipy,jsilter/scipy,ales-erjavec/scipy,grlee77/scipy,gef756/scipy,vhaasteren/scipy,mikebenfield/scipy,anntzer/scipy,sauliusl/scipy,surhudm/scipy,mingwpy/scipy,vhaasteren/scipy,jseabold/scipy,hainm/scipy,mhogg/scipy,andyfaff/scipy,vigna/scipy,aman-iitj/scipy,matthewalbani/scipy,kleskjr/scipy,jamestwebber/scipy,jamestwebber/scipy,scipy/scipy,cpaulik/scipy,grlee77/scipy,ilayn/scipy,gertingold/scipy,petebachant/scipy,sriki18/scipy,futurulus/scipy,sauliusl/scipy,jseabold/scipy,pyramania/scipy,scipy/scipy,surhudm/scipy,newemailjdm/scipy,pbrod/scipy,nvoron23/scipy,newemailjdm/scipy,piyush0609/scipy,ogrisel/scipy,larsmans/scipy,pyramania/scipy,andim/scipy,jonycgn/scipy,surhudm/scipy,richardotis/scipy,cpaulik/scipy,felipebetancur/scipy,vhaasteren/scipy,futurulus/scipy,mortonjt/scipy,nvoron23/scipy,kleskjr/scipy,petebachant/scipy,matthewalbani/scipy,nonhermitian/scipy,haudren/scipy,endolith/scipy,vigna/scipy,aman-iitj/scipy,njwilson23/scipy,maniteja123/scipy,ortylp/scipy,Newman101/scipy,felipebetancur/scipy,matthew-brett/scipy,mingwpy/scipy,ndchorley/scipy,sauliusl/scipy,fredrikw/scipy,hainm/scipy,anntzer/scipy,niknow/scipy,andim/scipy,chatcannon/scipy,mgaitan/scipy,Srisai85/scipy,mortonjt/scipy,zaxliu/scipy,apbard/scipy,sriki18/scipy,jakevdp/scipy,jor-/scipy,lukauskas/scipy,aarchiba/scipy,rmcgibbo/scipy,pnedunuri/scipy,josephcslater/scipy,minhlongdo/scipy,juliantaylor/scipy,Srisai85/scipy,fernand/scipy,futurulus/scipy,tylerjereddy/scipy,e-q/scipy,surhudm/scipy,matthew-brett/scipy,e-q/scipy,rgommers/scipy,lukauskas/scipy,rmcgibbo/scipy,nonhermitian/scipy,gdooper/scipy,zerothi/scipy,maniteja123/scipy,lhilt/scipy,vanpact/scipy,ogrisel/scipy,argriffing/scipy,juliantaylor/scipy,grlee77/scipy,ales-erjavec/scipy,rgommers/scipy,jjhelmus/scipy,bkendzior/scipy,mortonjt/scipy,matthewalbani/scipy,scipy/scipy,arokem/scipy,behzadnouri/scipy,anntzer/scipy,Srisai85/scipy,Shaswat27/scipy,witcxc/scipy,zxsted/scipy,fernand/scipy,gdooper/scipy,gfyoung/scipy,sonnyhu/scipy,haudren/scipy,WillieMaddox/scipy,zxsted/scipy,andyfaff/scipy,aman-iitj/scipy,vberaudi/scipy,fredrikw/scipy,FRidh/scipy,zerothi/scipy,futurulus/scipy,jor-/scipy,minhlongdo/scipy,endolith/scipy,mtrbean/scipy,aarchiba/scipy,minhlongdo/scipy,haudren/scipy,efiring/scipy,nvoron23/scipy,hainm/scipy,pbrod/scipy,raoulbq/scipy,scipy/scipy,richardotis/scipy,gef756/scipy,Gillu13/scipy,apbard/scipy,mdhaber/scipy,befelix/scipy,lukauskas/scipy,jonycgn/scipy,richardotis/scipy,endolith/scipy,nmayorov/scipy,tylerjereddy/scipy,Stefan-Endres/scipy,Eric89GXL/scipy,ChanderG/scipy,Newman101/scipy,person142/scipy,nonhermitian/scipy,mingwpy/scipy,ilayn/scipy,petebachant/scipy,WarrenWeckesser/scipy,larsmans/scipy,behzadnouri/scipy,raoulbq/scipy,lhilt/scipy,andim/scipy,ales-erjavec/scipy,gertingold/scipy,witcxc/scipy,njwilson23/scipy,Newman101/scipy,Gillu13/scipy,gertingold/scipy,zerothi/scipy,kalvdans/scipy,Gillu13/scipy,woodscn/scipy,andim/scipy,scipy/scipy,pyramania/scipy,Eric89GXL/scipy,FRidh/scipy,mikebenfield/scipy,nvoron23/scipy,mgaitan/scipy,ortylp/scipy,WillieMaddox/scipy,argriffing/scipy,hainm/scipy,sonnyhu/scipy,njwilson23/scipy,dch312/scipy,jjhelmus/scipy,zerothi/scipy,ortylp/scipy,dominicelse/scipy,Dapid/scipy,argriffing/scipy,futurulus/scipy,dominicelse/scipy,apbard/scipy,jseabold/scipy,Kamp9/scipy,aarchiba/scipy,efiring/scipy,sauliusl/scipy,zaxliu/scipy,ales-erjavec/scipy,rgommers/scipy,matthew-brett/scipy,aarchiba/scipy,mdhaber/scipy,petebachant/scipy,piyush0609/scipy,andyfaff/scipy,ilayn/scipy,maniteja123/scipy,minhlongdo/scipy,trankmichael/scipy,Newman101/scipy,Dapid/scipy,befelix/scipy,sriki18/scipy,Kamp9/scipy,piyush0609/scipy,Srisai85/scipy,befelix/scipy,ortylp/scipy,newemailjdm/scipy,woodscn/scipy,ndchorley/scipy,mortada/scipy,kleskjr/scipy,jakevdp/scipy,nmayorov/scipy,gertingold/scipy,vberaudi/scipy,ogrisel/scipy,pizzathief/scipy,person142/scipy,newemailjdm/scipy,pnedunuri/scipy,vanpact/scipy,Kamp9/scipy,jsilter/scipy,ales-erjavec/scipy,ndchorley/scipy,matthew-brett/scipy,felipebetancur/scipy,WarrenWeckesser/scipy,anielsen001/scipy,e-q/scipy,sriki18/scipy,vigna/scipy,trankmichael/scipy,gdooper/scipy,aeklant/scipy,maciejkula/scipy,ortylp/scipy,giorgiop/scipy,tylerjereddy/scipy,zaxliu/scipy,larsmans/scipy,mdhaber/scipy,mtrbean/scipy,giorgiop/scipy,cpaulik/scipy,Eric89GXL/scipy,richardotis/scipy,pbrod/scipy,felipebetancur/scipy,larsmans/scipy,vanpact/scipy,rmcgibbo/scipy,Stefan-Endres/scipy,fredrikw/scipy,vanpact/scipy,Srisai85/scipy,gdooper/scipy,jsilter/scipy,larsmans/scipy,perimosocordiae/scipy,richardotis/scipy,sauliusl/scipy,maciejkula/scipy,juliantaylor/scipy,jseabold/scipy,grlee77/scipy,jakevdp/scipy,kalvdans/scipy,witcxc/scipy,dominicelse/scipy,mtrbean/scipy,jor-/scipy,matthew-brett/scipy,lukauskas/scipy,mortada/scipy,kleskjr/scipy,arokem/scipy,apbard/scipy,vigna/scipy,josephcslater/scipy,matthewalbani/scipy,Gillu13/scipy,lhilt/scipy,ilayn/scipy,piyush0609/scipy,perimosocordiae/scipy,njwilson23/scipy,pnedunuri/scipy,mikebenfield/scipy,anntzer/scipy,pnedunuri/scipy,hainm/scipy,jseabold/scipy,jor-/scipy,Eric89GXL/scipy,WillieMaddox/scipy,pyramania/scipy,gdooper/scipy,Srisai85/scipy,sonnyhu/scipy,behzadnouri/scipy,andim/scipy,niknow/scipy,nmayorov/scipy,ndchorley/scipy,gfyoung/scipy,mhogg/scipy,anielsen001/scipy,jonycgn/scipy,giorgiop/scipy,anielsen001/scipy,perimosocordiae/scipy,newemailjdm/scipy,giorgiop/scipy,jakevdp/scipy,WarrenWeckesser/scipy,maciejkula/scipy,anntzer/scipy,WarrenWeckesser/scipy,jseabold/scipy,endolith/scipy,andim/scipy,bkendzior/scipy,ChanderG/scipy,nmayorov/scipy,witcxc/scipy,aman-iitj/scipy,dch312/scipy,person142/scipy,anielsen001/scipy,jjhelmus/scipy,cpaulik/scipy,niknow/scipy,petebachant/scipy,raoulbq/scipy,witcxc/scipy,argriffing/scipy,richardotis/scipy,efiring/scipy,zerothi/scipy,mortada/scipy,arokem/scipy,andyfaff/scipy,mortonjt/scipy,FRidh/scipy,andyfaff/scipy,niknow/scipy,befelix/scipy,Stefan-Endres/scipy,chatcannon/scipy,zxsted/scipy,aarchiba/scipy,pschella/scipy,mortonjt/scipy,pizzathief/scipy,Shaswat27/scipy,ilayn/scipy,mtrbean/scipy,pbrod/scipy,pizzathief/scipy,njwilson23/scipy,e-q/scipy,efiring/scipy,Stefan-Endres/scipy,njwilson23/scipy,dominicelse/scipy,bkendzior/scipy,mgaitan/scipy,apbard/scipy,gef756/scipy,behzadnouri/scipy,jakevdp/scipy,vhaasteren/scipy,pizzathief/scipy,josephcslater/scipy,woodscn/scipy,pnedunuri/scipy,ortylp/scipy,zxsted/scipy,maciejkula/scipy,mingwpy/scipy,jamestwebber/scipy,aeklant/scipy,Newman101/scipy,ChanderG/scipy,larsmans/scipy,fredrikw/scipy,rmcgibbo/scipy,mhogg/scipy,lhilt/scipy,mgaitan/scipy,chatcannon/scipy,vanpact/scipy,gertingold/scipy,anielsen001/scipy,pizzathief/scipy,woodscn/scipy,mhogg/scipy,haudren/scipy,efiring/scipy,jonycgn/scipy,Shaswat27/scipy,petebachant/scipy,Newman101/scipy,mikebenfield/scipy,rgommers/scipy,WillieMaddox/scipy,sauliusl/scipy,minhlongdo/scipy,pbrod/scipy,pnedunuri/scipy,anielsen001/scipy,vberaudi/scipy,dominicelse/scipy,maniteja123/scipy,WillieMaddox/scipy,andyfaff/scipy,vberaudi/scipy,Dapid/scipy,gfyoung/scipy,vberaudi/scipy,zaxliu/scipy,kleskjr/scipy,aeklant/scipy,perimosocordiae/scipy,perimosocordiae/scipy,Shaswat27/scipy,sonnyhu/scipy,FRidh/scipy,aeklant/scipy,cpaulik/scipy,mortada/scipy,Stefan-Endres/scipy,surhudm/scipy,rmcgibbo/scipy,gef756/scipy,vhaasteren/scipy,Shaswat27/scipy,mdhaber/scipy,mtrbean/scipy,tylerjereddy/scipy,nonhermitian/scipy,endolith/scipy,mortada/scipy,ndchorley/scipy,vanpact/scipy,behzadnouri/scipy,mgaitan/scipy,zaxliu/scipy,gfyoung/scipy,fredrikw/scipy,lukauskas/scipy,josephcslater/scipy,fredrikw/scipy,WillieMaddox/scipy,chatcannon/scipy,ChanderG/scipy,giorgiop/scipy,aeklant/scipy,dch312/scipy,zaxliu/scipy,trankmichael/scipy,fernand/scipy,jonycgn/scipy,pbrod/scipy,minhlongdo/scipy,scipy/scipy,gef756/scipy,piyush0609/scipy,mgaitan/scipy,Kamp9/scipy,Dapid/scipy,aman-iitj/scipy,arokem/scipy,mdhaber/scipy,piyush0609/scipy,vberaudi/scipy,Dapid/scipy,sriki18/scipy,mhogg/scipy,sonnyhu/scipy,ales-erjavec/scipy,efiring/scipy,WarrenWeckesser/scipy,befelix/scipy,nmayorov/scipy,ogrisel/scipy,nvoron23/scipy,rmcgibbo/scipy,vigna/scipy,jsilter/scipy,tylerjereddy/scipy,Shaswat27/scipy,mtrbean/scipy,raoulbq/scipy,zxsted/scipy,argriffing/scipy,lhilt/scipy,pschella/scipy,woodscn/scipy,mingwpy/scipy,josephcslater/scipy,juliantaylor/scipy,trankmichael/scipy,pschella/scipy,maciejkula/scipy,Kamp9/scipy,sriki18/scipy,pschella/scipy,dch312/scipy,niknow/scipy,chatcannon/scipy,jjhelmus/scipy,aman-iitj/scipy,mortada/scipy,ogrisel/scipy,FRidh/scipy,felipebetancur/scipy,fernand/scipy,lukauskas/scipy,argriffing/scipy,dch312/scipy,kalvdans/scipy,behzadnouri/scipy,bkendzior/scipy,maniteja123/scipy,gef756/scipy,jonycgn/scipy,kalvdans/scipy,felipebetancur/scipy,raoulbq/scipy,ilayn/scipy,mortonjt/scipy,woodscn/scipy,haudren/scipy,Eric89GXL/scipy,kleskjr/scipy,rgommers/scipy,Gillu13/scipy,trankmichael/scipy,maniteja123/scipy,gfyoung/scipy,juliantaylor/scipy,fernand/scipy,jjhelmus/scipy,zerothi/scipy,haudren/scipy,hainm/scipy,ndchorley/scipy,mikebenfield/scipy,jsilter/scipy,zxsted/scipy,mingwpy/scipy,bkendzior/scipy,niknow/scipy,jamestwebber/scipy,ChanderG/scipy,endolith/scipy,kalvdans/scipy,matthewalbani/scipy,pschella/scipy,cpaulik/scipy,Kamp9/scipy,ChanderG/scipy,fernand/scipy,perimosocordiae/scipy,mdhaber/scipy,jor-/scipy,nvoron23/scipy,giorgiop/scipy,person142/scipy,arokem/scipy,Dapid/scipy,surhudm/scipy,newemailjdm/scipy,FRidh/scipy,Stefan-Endres/scipy,raoulbq/scipy,e-q/scipy,pyramania/scipy,Eric89GXL/scipy,futurulus/scipy,chatcannon/scipy,person142/scipy