NEP: missingdata: Change the mask definition
NEP: missingdata: Change the mask definition

This change allows npy_bool to be a mask which always has payload
zero. This doesn't let combining masks with payloads to be a simple
'min' operation as the previous design, but allowing npy_bool as
the mask appears to be a very worthwhile tradeoff.

trankmichael/numpy,behzadnouri/numpy,madphysicist/numpy,naritta/numpy,dch312/numpy,GrimDerp/numpy,bmorris3/numpy,sonnyhu/numpy,ewmoore/numpy,stefanv/numpy,mindw/numpy,chiffa/numpy,cowlicks/numpy,CMartelLML/numpy,ogrisel/numpy,moreati/numpy,Srisai85/numpy,gfyoung/numpy,numpy/numpy,cowlicks/numpy,bmorris3/numpy,embray/numpy,dato-code/numpy,groutr/numpy,ahaldane/numpy,bringingheavendown/numpy,nbeaver/numpy,Yusa95/numpy,pbrod/numpy,skymanaditya1/numpy,jakirkham/numpy,ekalosak/numpy,Linkid/numpy,has2k1/numpy,empeeu/numpy,Linkid/numpy,leifdenby/numpy,cowlicks/numpy,mhvk/numpy,embray/numpy,yiakwy/numpy,drasmuss/numpy,rmcgibbo/numpy,rajathkumarmp/numpy,simongibbons/numpy,kirillzhuravlev/numpy,abalkin/numpy,embray/numpy,stefanv/numpy,mortada/numpy,skwbc/numpy,Linkid/numpy,dwf/numpy,endolith/numpy,MichaelAquilina/numpy,naritta/numpy,pizzathief/numpy,shoyer/numpy,pelson/numpy,njase/numpy,mhvk/numpy,musically-ut/numpy,mattip/numpy,groutr/numpy,mingwpy/numpy,behzadnouri/numpy,bringingheavendown/numpy,mortada/numpy,WarrenWeckesser/numpy,matthew-brett/numpy,dato-code/numpy,tdsmith/numpy,mwiebe/numpy,seberg/numpy,yiakwy/numpy,NextThought/pypy-numpy,ekalosak/numpy,dimasad/numpy,larsmans/numpy,ChristopherHogan/numpy,mindw/numpy,MichaelAquilina/numpy,rajathkumarmp/numpy,astrofrog/numpy,AustereCuriosity/numpy,Dapid/numpy,pbrod/numpy,maniteja123/numpy,rherault-insa/numpy,mathdd/numpy,BMJHayward/numpy,pyparallel/numpy,rajathkumarmp/numpy,rhythmsosad/numpy,MSeifert04/numpy,simongibbons/numpy,cjermain/numpy,abalkin/numpy,madphysicist/numpy,immerrr/numpy,SiccarPoint/numpy,stuarteberg/numpy,dato-code/numpy,stefanv/numpy,b-carter/numpy,MSeifert04/numpy,dwf/numpy,joferkington/numpy,mathdd/numpy,skwbc/numpy,tacaswell/numpy,anntzer/numpy,empeeu/numpy,stuarteberg/numpy,pizzathief/numpy,hainm/numpy,grlee77/numpy,ajdawson/numpy,matthew-brett/numpy,grlee77/numpy,gfyoung/numpy,dwillmer/numpy,rudimeier/numpy,embray/numpy,ViralLeadership/numpy,astrofrog/numpy,felipebetancur/numpy,sonnyhu/numpy,numpy/numpy,mortada/numpy,shoyer/numpy,nguyentu1602/numpy,ewmoore/numpy,seberg/numpy,gmcastil/numpy,madphysicist/numpy,githubmlai/numpy,bmorris3/numpy,stuarteberg/numpy,ahaldane/numpy,mathdd/numpy,nbeaver/numpy,charris/numpy,brandon-rhodes/numpy,chatcannon/numpy,tynn/numpy,pyparallel/numpy,charris/numpy,nbeaver/numpy,chatcannon/numpy,SunghanKim/numpy,jakirkham/numpy,mortada/numpy,rherault-insa/numpy,pbrod/numpy,WarrenWeckesser/numpy,NextThought/pypy-numpy,Srisai85/numpy,githubmlai/numpy,trankmichael/numpy,felipebetancur/numpy,mhvk/numpy,jankoslavic/numpy,joferkington/numpy,Srisai85/numpy,bringingheavendown/numpy,ahaldane/numpy,pbrod/numpy,moreati/numpy,madphysicist/numpy,charris/numpy,musically-ut/numpy,ogrisel/numpy,Anwesh43/numpy,njase/numpy,charris/numpy,kiwifb/numpy,mindw/numpy,Eric89GXL/numpy,ContinuumIO/numpy,jschueller/numpy,naritta/numpy,simongibbons/numpy,ogrisel/numpy,skymanaditya1/numpy,chiffa/numpy,CMartelLML/numpy,jschueller/numpy,andsor/numpy,simongibbons/numpy,andsor/numpy,jankoslavic/numpy,tdsmith/numpy,argriffing/numpy,Eric89GXL/numpy,ESSS/numpy,tacaswell/numpy,bmorris3/numpy,cjermain/numpy,Anwesh43/numpy,seberg/numpy,stefanv/numpy,ahaldane/numpy,has2k1/numpy,rmcgibbo/numpy,Yusa95/numpy,anntzer/numpy,maniteja123/numpy,ChristopherHogan/numpy,jorisvandenbossche/numpy,ContinuumIO/numpy,sonnyhu/numpy,ahaldane/numpy,sigma-random/numpy,rgommers/numpy,mattip/numpy,trankmichael/numpy,grlee77/numpy,nguyentu1602/numpy,rgommers/numpy,utke1/numpy,mindw/numpy,tdsmith/numpy,jschueller/numpy,grlee77/numpy,Linkid/numpy,mwiebe/numpy,ESSS/numpy,pdebuyl/numpy,sinhrks/numpy,ewmoore/numpy,GaZ3ll3/numpy,leifdenby/numpy,brandon-rhodes/numpy,BMJHayward/numpy,WillieMaddox/numpy,gmcastil/numpy,CMartelLML/numpy,bertrand-l/numpy,jankoslavic/numpy,Anwesh43/numpy,dch312/numpy,ajdawson/numpy,Yusa95/numpy,ddasilva/numpy,numpy/numpy,dch312/numpy,anntzer/numpy,dato-code/numpy,ddasilva/numpy,immerrr/numpy,pdebuyl/numpy,bertrand-l/numpy,MSeifert04/numpy,matthew-brett/numpy,hainm/numpy,KaelChen/numpy,ContinuumIO/numpy,gfyoung/numpy,embray/numpy,moreati/numpy,GaZ3ll3/numpy,mingwpy/numpy,dwf/numpy,WarrenWeckesser/numpy,dimasad/numpy,leifdenby/numpy,NextThought/pypy-numpy,sinhrks/numpy,WillieMaddox/numpy,sonnyhu/numpy,MaPePeR/numpy,shoyer/numpy,SiccarPoint/numpy,KaelChen/numpy,SunghanKim/numpy,nguyentu1602/numpy,mattip/numpy,rmcgibbo/numpy,immerrr/numpy,seberg/numpy,sigma-random/numpy,stefanv/numpy,dimasad/numpy,cowlicks/numpy,Yusa95/numpy,dwillmer/numpy,AustereCuriosity/numpy,utke1/numpy,SunghanKim/numpy,kirillzhuravlev/numpy,skwbc/numpy,ViralLeadership/numpy,yiakwy/numpy,empeeu/numpy,MSeifert04/numpy,ssanderson/numpy,ChristopherHogan/numpy,argriffing/numpy,pelson/numpy,ekalosak/numpy,larsmans/numpy,sigma-random/numpy,grlee77/numpy,MaPePeR/numpy,ESSS/numpy,kiwifb/numpy,mingwpy/numpy,chiffa/numpy,ChristopherHogan/numpy,pelson/numpy,rajathkumarmp/numpy,endolith/numpy,tynn/numpy,mathdd/numpy,skymanaditya1/numpy,anntzer/numpy,drasmuss/numpy,ssanderson/numpy,cjermain/numpy,naritta/numpy,KaelChen/numpy,jonathanunderwood/numpy,behzadnouri/numpy,b-carter/numpy,kiwifb/numpy,rudimeier/numpy,simongibbons/numpy,BabeNovelty/numpy,CMartelLML/numpy,hainm/numpy,Eric89GXL/numpy,WillieMaddox/numpy,shoyer/numpy,astrofrog/numpy,pdebuyl/numpy,rhythmsosad/numpy,ewmoore/numpy,Dapid/numpy,ssanderson/numpy,tynn/numpy,hainm/numpy,SiccarPoint/numpy,empeeu/numpy,drasmuss/numpy,argriffing/numpy,ekalosak/numpy,b-carter/numpy,has2k1/numpy,pyparallel/numpy,brandon-rhodes/numpy,pdebuyl/numpy,BMJHayward/numpy,felipebetancur/numpy,kirillzhuravlev/numpy,pelson/numpy,githubmlai/numpy,madphysicist/numpy,mwiebe/numpy,mingwpy/numpy,rudimeier/numpy,jakirkham/numpy,pbrod/numpy,NextThought/pypy-numpy,jorisvandenbossche/numpy,mhvk/numpy,shoyer/numpy,tdsmith/numpy,dwillmer/numpy,rhythmsosad/numpy,gmcastil/numpy,ChanderG/numpy,nguyentu1602/numpy,sigma-random/numpy,sinhrks/numpy,tacaswell/numpy,endolith/numpy,matthew-brett/numpy,GrimDerp/numpy,astrofrog/numpy,njase/numpy,dch312/numpy,rudimeier/numpy,jankoslavic/numpy,joferkington/numpy,pelson/numpy,rgommers/numpy,ogrisel/numpy,musically-ut/numpy,Eric89GXL/numpy,pizzathief/numpy,chatcannon/numpy,numpy/numpy,KaelChen/numpy,MaPePeR/numpy,ChanderG/numpy,felipebetancur/numpy,sinhrks/numpy,larsmans/numpy,GaZ3ll3/numpy,utke1/numpy,mhvk/numpy,rmcgibbo/numpy,pizzathief/numpy,yiakwy/numpy,bertrand-l/numpy,endolith/numpy,cjermain/numpy,GrimDerp/numpy,BabeNovelty/numpy,andsor/numpy,solarjoe/numpy,trankmichael/numpy,jakirkham/numpy,rgommers/numpy,dwillmer/numpy,Dapid/numpy,ajdawson/numpy,MichaelAquilina/numpy,GaZ3ll3/numpy,musically-ut/numpy,groutr/numpy,andsor/numpy,rhythmsosad/numpy,skymanaditya1/numpy,ddasilva/numpy,jonathanunderwood/numpy,GrimDerp/numpy,dwf/numpy,ewmoore/numpy,stuarteberg/numpy,githubmlai/numpy,astrofrog/numpy,MSeifert04/numpy,ViralLeadership/numpy,SiccarPoint/numpy,mattip/numpy,dimasad/numpy,jorisvandenbossche/numpy,jschueller/numpy,brandon-rhodes/numpy,solarjoe/numpy,Anwesh43/numpy,has2k1/numpy,ogrisel/numpy,jonathanunderwood/numpy,abalkin/numpy,jorisvandenbossche/numpy,joferkington/numpy,MichaelAquilina/numpy,matthew-brett/numpy,MaPePeR/numpy,BabeNovelty/numpy,BMJHayward/numpy,dwf/numpy,jorisvandenbossche/numpy,AustereCuriosity/numpy,jakirkham/numpy,WarrenWeckesser/numpy,larsmans/numpy,SunghanKim/numpy,immerrr/numpy,rherault-insa/numpy,WarrenWeckesser/numpy,kirillzhuravlev/numpy,maniteja123/numpy,ChanderG/numpy,pizzathief/numpy,BabeNovelty/numpy,solarjoe/numpy,Srisai85/numpy,ChanderG/numpy,ajdawson/numpy