DOC: Update ufunc documentation to mention generalized ufuncs.
DOC: Update ufunc documentation to mention generalized ufuncs.

Also ensure that __array_ufunc__ is referenced in the output type
determination.

Eric89GXL/numpy,mattip/numpy,shoyer/numpy,WarrenWeckesser/numpy,WarrenWeckesser/numpy,ahaldane/numpy,seberg/numpy,simongibbons/numpy,rgommers/numpy,madphysicist/numpy,pbrod/numpy,jakirkham/numpy,grlee77/numpy,Eric89GXL/numpy,numpy/numpy,WarrenWeckesser/numpy,endolith/numpy,anntzer/numpy,ahaldane/numpy,pdebuyl/numpy,mhvk/numpy,grlee77/numpy,mhvk/numpy,grlee77/numpy,charris/numpy,rgommers/numpy,jorisvandenbossche/numpy,grlee77/numpy,simongibbons/numpy,anntzer/numpy,pizzathief/numpy,gfyoung/numpy,mattip/numpy,pdebuyl/numpy,ahaldane/numpy,numpy/numpy,jakirkham/numpy,MSeifert04/numpy,jorisvandenbossche/numpy,numpy/numpy,ahaldane/numpy,WarrenWeckesser/numpy,shoyer/numpy,WarrenWeckesser/numpy,tynn/numpy,abalkin/numpy,MSeifert04/numpy,anntzer/numpy,madphysicist/numpy,endolith/numpy,pizzathief/numpy,pdebuyl/numpy,charris/numpy,pbrod/numpy,pbrod/numpy,endolith/numpy,Eric89GXL/numpy,abalkin/numpy,mhvk/numpy,jorisvandenbossche/numpy,seberg/numpy,pizzathief/numpy,rgommers/numpy,simongibbons/numpy,MSeifert04/numpy,abalkin/numpy,shoyer/numpy,madphysicist/numpy,pbrod/numpy,mhvk/numpy,tynn/numpy,endolith/numpy,Eric89GXL/numpy,simongibbons/numpy,simongibbons/numpy,pdebuyl/numpy,pizzathief/numpy,jakirkham/numpy,charris/numpy,tynn/numpy,jorisvandenbossche/numpy,madphysicist/numpy,shoyer/numpy,mhvk/numpy,rgommers/numpy,pizzathief/numpy,anntzer/numpy,MSeifert04/numpy,mattip/numpy,gfyoung/numpy,seberg/numpy,ahaldane/numpy,shoyer/numpy,MSeifert04/numpy,gfyoung/numpy,jorisvandenbossche/numpy,pbrod/numpy,seberg/numpy,jakirkham/numpy,madphysicist/numpy,mattip/numpy,jakirkham/numpy,grlee77/numpy,numpy/numpy,charris/numpy