This speeds up the lightmapper by about 10% with no visible impact. A
comparison is up here:
https://tmm.cx/nextcloud/s/Log1eAXen1dJzBz
AMD Ryzen 7 1700 Eight-Core Processor
Sponza scene
pcg32
256/256/high 00:10:13
256/256/medium 00:02:50
256/256/low 00:01:11
xorshift
256/256/high 00:09:32
256/256/medium 00:02:34
256/256/low 00:01:05
-Fixes to unwrapper (remove degenerates), makes Thekla not crash
-Added optional cancel button in EditorProgress
-Added function to force processing of events (needed for cancel button)