Moved the polygonization code to the specific regions that are being polygonized.

Also, maxPoints no longer has confusing semantics.
Added static ZERO, UNIT_X, UNIT_Y, UNIT_Z, and ONE fields to Vector.
Reduced some code duplication in the regions.
Fixed a typo.
Added a ConvexPolyhedralRegion and selector
Added the polyhedral selector to //sel.