trim curves for all surfaces lie between 0 and 1. And add routines
to merge the curves and surfaces from two shells into one, and to
split the trim curves into their piecewise linear segments and then
reassemble them into trim curves.
[git-p4: depot-paths = "//depot/solvespace/": change = 1905]
Add stubs for functions to perform Booleans, and get rid of mesh
stuff, including the kd tree accelerated snap to vertex (which
should not be required if the shell triangulation performs as it
should).
Also check that a sketch is not self-intersecting before extruding
it or whatever. This is dead slow, needs n*log(n) implementation.
[git-p4: depot-paths = "//depot/solvespace/": change = 1902]
Jonathan Westhues