Make setup-type methods internal
Make setup-type methods internal

Add leading underscores to methods not intended to be user-facing in
Voronoi. Rename some of them for LL style and to be more descriptive.

Carralex/landlab,cmshobe/landlab,laijingtao/landlab,laijingtao/landlab,Carralex/landlab,RondaStrauch/landlab,amandersillinois/landlab,landlab/landlab,landlab/landlab,csherwood-usgs/landlab,RondaStrauch/landlab,SiccarPoint/landlab,ManuSchmi88/landlab,ManuSchmi88/landlab,SiccarPoint/landlab,ManuSchmi88/landlab,csherwood-usgs/landlab,amandersillinois/landlab,Carralex/landlab,cmshobe/landlab,landlab/landlab,cmshobe/landlab,RondaStrauch/landlab