fix [#30740] N-panel addon toggle operators crash Blender after screen change (Fatal Python error: GC object already tracked)

rectangular leaves since bmesh.

use Tr as translucency and use reflection coords for 'map_refl' setting.

Some cosmetics ... .

When exporting structures from Blender into a PDB file it happened 
sometimes that the xyz positions of the atoms weren't correctly 
stored. Bug fixed.

import. I have no idea why that happened out of a sudden. Anyway, I removed
this bug.

In this situation, the script creates a dummy root bone... But code was buggy (and import of non-rotating bones was too).

Update to 2.64, and make the ticker slower to not eat CPUs.

Fix encoding error (please be carful with this - even though using non-ascii chars in code/comments is not a good idea, my bad). Thanks Irie Shinsuke for the report!

patch by Alan Hudson

apply part of the patch included with the report - by Alan Hudson.

[[Split portion of a mixed commit.]]

[[Split portion of a mixed commit.]]

[[Split portion of a mixed commit.]]

support for loading DXF's with thumbnails (just skip them)

Made a few refactoring/style cleanup of code here...

code cleanup: python - pass multiple args to string startswith() / endswith() functions rather than calling multiple times.