Blender Git Loki

Islands 'TubeCase' WIP: More fixes, everything is mostly hooked up now.

Quick tests shows everything seems to work as expected so far.
And, divine surprise, performances seem pretty good!

Note we limit AStar to a small number of steps (4 currently),
reasoning is, if we map highpoly (dst) onto lowpoly (src), this should be
enough in most cases (smaller dst polys onto larger ones are unlikely to span
over more than two or three src polys). And in reverse case, taking care of
islands does not make much sense anyway, result shall be crappy anyway.

Remaining TODOs:
* Finish cutting edges handling (right now nothing is done yet to solve issues!).
* Cleanup/reorganization (AStar part has been designed as generic as possible,
will go to BLI), names, etc.
* Double, triple and quadruple checks of mem handling (*very* easy to get a mem leak
in such code :/ ).