DOC: Fix examples in npyio.py to properly import StringIO.
DOC: Fix examples in npyio.py to properly import StringIO.

In two places they were doing

    >>> from StringIO import StringIO

Since Python 2.6 that should be

    >>> from io import StringIO

Closes #5995.

mhvk/numpy,nguyentu1602/numpy,Yusa95/numpy,dwillmer/numpy,AustereCuriosity/numpy,ahaldane/numpy,musically-ut/numpy,rajathkumarmp/numpy,ekalosak/numpy,Anwesh43/numpy,skwbc/numpy,moreati/numpy,jakirkham/numpy,njase/numpy,hainm/numpy,pbrod/numpy,mathdd/numpy,simongibbons/numpy,bmorris3/numpy,sonnyhu/numpy,CMartelLML/numpy,sinhrks/numpy,gfyoung/numpy,Dapid/numpy,SiccarPoint/numpy,dimasad/numpy,jankoslavic/numpy,sinhrks/numpy,felipebetancur/numpy,ViralLeadership/numpy,mwiebe/numpy,BabeNovelty/numpy,mhvk/numpy,BabeNovelty/numpy,argriffing/numpy,ChristopherHogan/numpy,leifdenby/numpy,sonnyhu/numpy,has2k1/numpy,rgommers/numpy,pizzathief/numpy,stuarteberg/numpy,jakirkham/numpy,seberg/numpy,gmcastil/numpy,pyparallel/numpy,SiccarPoint/numpy,empeeu/numpy,drasmuss/numpy,sonnyhu/numpy,nguyentu1602/numpy,pbrod/numpy,simongibbons/numpy,anntzer/numpy,joferkington/numpy,ChanderG/numpy,Eric89GXL/numpy,Yusa95/numpy,utke1/numpy,Srisai85/numpy,rhythmsosad/numpy,pdebuyl/numpy,ekalosak/numpy,githubmlai/numpy,maniteja123/numpy,bringingheavendown/numpy,pbrod/numpy,ahaldane/numpy,GaZ3ll3/numpy,chatcannon/numpy,jorisvandenbossche/numpy,ssanderson/numpy,has2k1/numpy,trankmichael/numpy,WillieMaddox/numpy,nbeaver/numpy,GrimDerp/numpy,solarjoe/numpy,rgommers/numpy,felipebetancur/numpy,chiffa/numpy,kiwifb/numpy,drasmuss/numpy,tacaswell/numpy,ssanderson/numpy,MaPePeR/numpy,jorisvandenbossche/numpy,jschueller/numpy,Srisai85/numpy,ChanderG/numpy,kirillzhuravlev/numpy,shoyer/numpy,grlee77/numpy,CMartelLML/numpy,gmcastil/numpy,nguyentu1602/numpy,ESSS/numpy,Yusa95/numpy,ChristopherHogan/numpy,mathdd/numpy,anntzer/numpy,jschueller/numpy,MichaelAquilina/numpy,rajathkumarmp/numpy,KaelChen/numpy,madphysicist/numpy,endolith/numpy,felipebetancur/numpy,simongibbons/numpy,GaZ3ll3/numpy,numpy/numpy,ssanderson/numpy,jakirkham/numpy,ContinuumIO/numpy,SunghanKim/numpy,charris/numpy,chatcannon/numpy,kirillzhuravlev/numpy,drasmuss/numpy,Dapid/numpy,skymanaditya1/numpy,pbrod/numpy,solarjoe/numpy,ContinuumIO/numpy,charris/numpy,nbeaver/numpy,dwillmer/numpy,moreati/numpy,bmorris3/numpy,kirillzhuravlev/numpy,njase/numpy,SunghanKim/numpy,shoyer/numpy,pdebuyl/numpy,tynn/numpy,ChristopherHogan/numpy,ahaldane/numpy,bertrand-l/numpy,dwillmer/numpy,kiwifb/numpy,Srisai85/numpy,WarrenWeckesser/numpy,joferkington/numpy,Eric89GXL/numpy,rgommers/numpy,charris/numpy,seberg/numpy,skwbc/numpy,cjermain/numpy,madphysicist/numpy,rudimeier/numpy,has2k1/numpy,jorisvandenbossche/numpy,grlee77/numpy,mingwpy/numpy,jankoslavic/numpy,jakirkham/numpy,tacaswell/numpy,Eric89GXL/numpy,mwiebe/numpy,WarrenWeckesser/numpy,ContinuumIO/numpy,sinhrks/numpy,AustereCuriosity/numpy,b-carter/numpy,WarrenWeckesser/numpy,gmcastil/numpy,ddasilva/numpy,bringingheavendown/numpy,groutr/numpy,mathdd/numpy,felipebetancur/numpy,jschueller/numpy,rudimeier/numpy,Yusa95/numpy,tacaswell/numpy,trankmichael/numpy,jonathanunderwood/numpy,WarrenWeckesser/numpy,madphysicist/numpy,mhvk/numpy,jonathanunderwood/numpy,KaelChen/numpy,ekalosak/numpy,hainm/numpy,maniteja123/numpy,empeeu/numpy,leifdenby/numpy,dimasad/numpy,mattip/numpy,githubmlai/numpy,grlee77/numpy,hainm/numpy,shoyer/numpy,groutr/numpy,cjermain/numpy,jakirkham/numpy,b-carter/numpy,MSeifert04/numpy,MSeifert04/numpy,trankmichael/numpy,mathdd/numpy,GrimDerp/numpy,MichaelAquilina/numpy,jorisvandenbossche/numpy,empeeu/numpy,jankoslavic/numpy,githubmlai/numpy,hainm/numpy,mattip/numpy,Dapid/numpy,rajathkumarmp/numpy,maniteja123/numpy,mingwpy/numpy,seberg/numpy,Eric89GXL/numpy,argriffing/numpy,abalkin/numpy,endolith/numpy,Linkid/numpy,numpy/numpy,jankoslavic/numpy,ahaldane/numpy,utke1/numpy,behzadnouri/numpy,rherault-insa/numpy,bmorris3/numpy,mattip/numpy,sinhrks/numpy,kirillzhuravlev/numpy,jorisvandenbossche/numpy,mhvk/numpy,nbeaver/numpy,rgommers/numpy,simongibbons/numpy,trankmichael/numpy,MaPePeR/numpy,GaZ3ll3/numpy,Srisai85/numpy,pizzathief/numpy,AustereCuriosity/numpy,pizzathief/numpy,skwbc/numpy,stuarteberg/numpy,kiwifb/numpy,rhythmsosad/numpy,MaPePeR/numpy,CMartelLML/numpy,rhythmsosad/numpy,empeeu/numpy,BabeNovelty/numpy,rhythmsosad/numpy,dimasad/numpy,njase/numpy,GaZ3ll3/numpy,Anwesh43/numpy,behzadnouri/numpy,pdebuyl/numpy,musically-ut/numpy,chiffa/numpy,ekalosak/numpy,mingwpy/numpy,moreati/numpy,SiccarPoint/numpy,numpy/numpy,numpy/numpy,MichaelAquilina/numpy,sonnyhu/numpy,Linkid/numpy,rherault-insa/numpy,chatcannon/numpy,joferkington/numpy,GrimDerp/numpy,WillieMaddox/numpy,rudimeier/numpy,Linkid/numpy,ahaldane/numpy,abalkin/numpy,BabeNovelty/numpy,mwiebe/numpy,rudimeier/numpy,grlee77/numpy,ChristopherHogan/numpy,ESSS/numpy,shoyer/numpy,abalkin/numpy,jschueller/numpy,behzadnouri/numpy,rajathkumarmp/numpy,endolith/numpy,ddasilva/numpy,ViralLeadership/numpy,utke1/numpy,jonathanunderwood/numpy,bmorris3/numpy,b-carter/numpy,githubmlai/numpy,MaPePeR/numpy,skymanaditya1/numpy,SunghanKim/numpy,groutr/numpy,solarjoe/numpy,Linkid/numpy,madphysicist/numpy,musically-ut/numpy,leifdenby/numpy,has2k1/numpy,charris/numpy,pbrod/numpy,KaelChen/numpy,cjermain/numpy,tynn/numpy,mingwpy/numpy,Anwesh43/numpy,seberg/numpy,Anwesh43/numpy,pyparallel/numpy,mattip/numpy,GrimDerp/numpy,ChanderG/numpy,MSeifert04/numpy,rherault-insa/numpy,MichaelAquilina/numpy,stuarteberg/numpy,shoyer/numpy,grlee77/numpy,MSeifert04/numpy,CMartelLML/numpy,skymanaditya1/numpy,ESSS/numpy,pyparallel/numpy,SunghanKim/numpy,gfyoung/numpy,bringingheavendown/numpy,musically-ut/numpy,pizzathief/numpy,skymanaditya1/numpy,SiccarPoint/numpy,ddasilva/numpy,anntzer/numpy,joferkington/numpy,WarrenWeckesser/numpy,anntzer/numpy,bertrand-l/numpy,mhvk/numpy,simongibbons/numpy,pizzathief/numpy,bertrand-l/numpy,dwillmer/numpy,chiffa/numpy,MSeifert04/numpy,stuarteberg/numpy,madphysicist/numpy,ChanderG/numpy,nguyentu1602/numpy,cjermain/numpy,ViralLeadership/numpy,gfyoung/numpy,tynn/numpy,dimasad/numpy,pdebuyl/numpy,argriffing/numpy,endolith/numpy,KaelChen/numpy,WillieMaddox/numpy