COLLADA branch: exporter takes face smoothness flag into account.

Previously only smooth normals were written for each mesh. Now proper normals are written for flat faces too. Since smooth faces may share normals, writing of duplicate normals is avoided.
COLLADA branch: import mesh smoothing info. Normal values from DAE are not assigned to vertices but are used to flag faces as smooth or flat. This trick works.
COLLADA branch: merge from trunk -r 26429:26848.
COLLADA branch: remove signed/unsigned comparison warnings.
COLLADA branch:
* fix bug in normals import code - could crash on meshes with ngons
* disabled creation of empties on armature import (used for debugging)
* fix memleak (temporary FCurves were not freed)
COLLADA branch: export vertex colors. Write only active layer for now, all layer export can be added later easily.
COLLADA branch: fix bug #21768 - animation channel target was incomplete for translation and scaling animation.
COLLADA branch: importer fix - loc/scale animation was being read incorrectly. Discovered this while fixing bug #21768.
COLLADA branch: import matrix animations.
Discovered that importer sets object parents incorrectly - still got to figure out how to fix.
COLLADA branch: merge from trunk -r 26848:28015.
COLLADA branch: fix importer's parenting problem.
COLLADA branch: fix bug #21989 - test for empty uv sets.
Plus made animation import messages more informative.
COLLADA branch:
* partially fix #22388 by appending mesh object name to skin controller id (according to the patch provided by Tod Liverseed) (exporter). Importer still incorrectly handles the case when multiple meshes are linked to a single armature.
* add GPL blocks mentioning contributors. Hopefully didn't miss anyone.
COLLADA branch: change texture coordinate parameter names from X and Y to spec-compliant S and T.
COLLADA branch: fix bug #22388.
Do not create multiple armatures when multiple controllers share armature.
COLLADA branch: patch by Tod Liverseed.
* fix exported values of material transparency, emission and reflectivity
* add extra double_sided tag in GoogleEarth and MAX3D profiles
COLLADA branch: keep bone animation sampling keys in ascending order.
COLLADA branch: support <instance_node> import. Fixes bug #21954.
COLLADA branch: merge from trunk -r 28015:31610.