Goal of this commit is to support NGons for boolean modifier
(currently mesh is being tessellated before performing boolean
operation) and also solve the limitation of loosing edge custom
data layers after boolean operation is performed.
Main idea is to make it so boolean modifier uses Carve library
directly via it's C-API, avoiding BSP intermediate level which
was doubling amount of memory needed for the operation and which
also used quite reasonable amount of overhead time.