Core :
- fix HashString function (accept empty strings).
- fix ResourceManager request processing.
Graphic :
- update Material system
- add material loading
- update mesh loading with material
UnitTest :
- update levels
- use material system in level6
MaterialCompiler :
- update
MeshCompiler :
- add material compilation
TexCompiler :
- update
data :
- add level 6 data
- update existing meshes ( sibenik.dae becomes level5.dae )