from dan grauer (kromar)

With change use_map_color_emission (which is for volumetrics only) to use_map_emit.

also ignore generated face-images (which have no file path).

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

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

Changed how mtl_mat names are generated, so that we can still be sure to always have a unique mtl_name for each key (mat_name, tex_name), yet avoiding to add tex name to mat when not needed.

finished

This should fix [#31801] "OBJ importer doesn't import smoothing groups as sharp edges" reported by Tom Penn.

There was code to mark edges as sharp but it was disabled as being too slow. Found a quicker way using bmesh.
Reviewed by Campbell.

Now the importer assigns the object the same name as the object data.
Reviewed by Campbell.

This should fix [#31835] "OBJ Importer corrupts a model (crash in edit mode)" reported by paul geraskin.

The importer did the mesh validation before calculating edges (should be the other way around).
Reviewed by Campbell.

bpy_extras.io_utils.path_reference() expects a real dir as base_src, not the blend file name!

update addons enabled by default to use 'faces -> tessfaces' also grease pencil scatter and quake map export.

from Martijn Berger (juicyfruit) 

with some edits for efficient dict access.

from ed gautier (edddy) 

indentation edits and copy pyrimid from contrib (where I had made some edits), removed so this wont happen again.

Fix #28816: Error when importing obj file with texture due to api change

Update obj importer and xcf importer to use new post-texface api.

Plus a few styling enhancements.

[[Split portion of a mixed commit.]]

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