from Alexander Gessler (aramis_acg)

This patch extends the 3DS importer and exporter to have better material support and unifies their respective feature sets.

This includes:
- UV scale,offset
- tiling/wrap modes
- improved conversion of mapping targets
- better warnings

Additionally, the exporter now handles specular, opacity and normal maps correctly (the importer did this already). (I think the way how textures were written previously was non 3DS-compliant).

I tested this against assimp's 3DS test suite [1] as well as my personal 3DS test sets. Exported 3DS files were successfully read by FBXConv and assimp.

[1] http://assimp.svn.sourceforge.net/viewvc/assimp/trunk/test/

from Alexander Gessler (aramis_acg) 

- pep8 edits for after effects script.

objects with too large arrays will be skipped.

Plus a few styling enhancements.

[[Split portion of a mixed commit.]]

Adding UNDO flag to import operators. Made this only for trunk addons.

previous order deprecated.

- remove/comment unused variables
- remove unused imports
- fixed some bugs using incorrect variables

- fbx default use_selected to False