DOC: interpolate:  make constants private.
DOC: interpolate:  make constants private.

rgommers/scipy,andyfaff/scipy,mdhaber/scipy,mdhaber/scipy,perimosocordiae/scipy,ilayn/scipy,endolith/scipy,Stefan-Endres/scipy,perimosocordiae/scipy,scipy/scipy,anntzer/scipy,endolith/scipy,ilayn/scipy,ilayn/scipy,WarrenWeckesser/scipy,anntzer/scipy,mdhaber/scipy,andyfaff/scipy,scipy/scipy,scipy/scipy,perimosocordiae/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,endolith/scipy,mdhaber/scipy,WarrenWeckesser/scipy,andyfaff/scipy,anntzer/scipy,anntzer/scipy,mdhaber/scipy,rgommers/scipy,andyfaff/scipy,andyfaff/scipy,ilayn/scipy,rgommers/scipy,anntzer/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,WarrenWeckesser/scipy,endolith/scipy,rgommers/scipy,ilayn/scipy,scipy/scipy,perimosocordiae/scipy,andyfaff/scipy,ilayn/scipy,scipy/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,endolith/scipy,rgommers/scipy,Stefan-Endres/scipy,scipy/scipy,WarrenWeckesser/scipy,endolith/scipy,anntzer/scipy,mdhaber/scipy