Collada

Collada
- collada 1.5.0 textures are readable now
- cube and volume maps and mip initializations are skipped
Material system
- unified texture types. Added lightmap, displacement, reflection and 'unknown'. Everyone should be happy now (intending to remove ambient textures from the API).

ComputeUV
Changed mapping axis property to vec3
Adapted step
WARN: produces mirrored uv coords now. LH issue.

IRR
Updated to new texture types

3DS
Updated to new texture types

NFF
Updated to new texture types

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@340 67173fc5-114c-0410-ac8e-9d2fd5bffc1f