Use os.path.join for cross-platformness
use Polygon module for tesselation in extractor thread
use glutPostRedisplay() to cause redraw, for better interactivity
Use vertex arrays for faster converstion
Merge remote-tracking branch 'origin/cross_validation' into cross_validation

Also, fix text lighting
fixed index bug
Merge remote-tracking branch 'thouis/3d_extractor' into cross_validation
new triangulator and using post redisplay