DOC: add intersphinx mapping to numpy
DOC: add intersphinx mapping to numpy

There are already some references in the API docs to numpy functions, but the links did not yet work up to now.
pratapvardhan/pandas,rs2/pandas,winklerand/pandas,zfrenchee/pandas,GuessWhoSamFoo/pandas,jorisvandenbossche/pandas,jmmease/pandas,datapythonista/pandas,jmmease/pandas,jreback/pandas,toobaz/pandas,datapythonista/pandas,GuessWhoSamFoo/pandas,DGrady/pandas,jreback/pandas,cython-testbed/pandas,TomAugspurger/pandas,kdebrab/pandas,winklerand/pandas,amolkahat/pandas,dsm054/pandas,winklerand/pandas,GuessWhoSamFoo/pandas,DGrady/pandas,cython-testbed/pandas,amolkahat/pandas,rs2/pandas,zfrenchee/pandas,louispotok/pandas,pandas-dev/pandas,Winand/pandas,kdebrab/pandas,kdebrab/pandas,kdebrab/pandas,MJuddBooth/pandas,winklerand/pandas,nmartensen/pandas,louispotok/pandas,pratapvardhan/pandas,pratapvardhan/pandas,jorisvandenbossche/pandas,harisbal/pandas,gfyoung/pandas,linebp/pandas,DGrady/pandas,jmmease/pandas,jreback/pandas,DGrady/pandas,rs2/pandas,DGrady/pandas,rs2/pandas,linebp/pandas,cbertinato/pandas,kdebrab/pandas,datapythonista/pandas,pratapvardhan/pandas,pandas-dev/pandas,MJuddBooth/pandas,linebp/pandas,GuessWhoSamFoo/pandas,Winand/pandas,harisbal/pandas,nmartensen/pandas,pratapvardhan/pandas,Winand/pandas,louispotok/pandas,cbertinato/pandas,datapythonista/pandas,winklerand/pandas,jreback/pandas,DGrady/pandas,amolkahat/pandas,cython-testbed/pandas,jmmease/pandas,MJuddBooth/pandas,harisbal/pandas,cython-testbed/pandas,TomAugspurger/pandas,dsm054/pandas,gfyoung/pandas,pandas-dev/pandas,cython-testbed/pandas,jreback/pandas,winklerand/pandas,dsm054/pandas,TomAugspurger/pandas,MJuddBooth/pandas,gfyoung/pandas,linebp/pandas,toobaz/pandas,amolkahat/pandas,pandas-dev/pandas,zfrenchee/pandas,linebp/pandas,nmartensen/pandas,toobaz/pandas,gfyoung/pandas,cbertinato/pandas,zfrenchee/pandas,toobaz/pandas,zfrenchee/pandas,louispotok/pandas,cbertinato/pandas,cbertinato/pandas,Winand/pandas,jmmease/pandas,jorisvandenbossche/pandas,MJuddBooth/pandas,toobaz/pandas,nmartensen/pandas,Winand/pandas,harisbal/pandas,jorisvandenbossche/pandas,amolkahat/pandas,Winand/pandas,dsm054/pandas,gfyoung/pandas,nmartensen/pandas,nmartensen/pandas,linebp/pandas,harisbal/pandas,louispotok/pandas,GuessWhoSamFoo/pandas,dsm054/pandas,jmmease/pandas,TomAugspurger/pandas