Updated shaders

Added support for billboards (rendertechniques support is coming) -
Doesn't support lighting well for now
Added support for vertex coloring
Added AUTO_TEXCOORDS parameter support to PhongLighting UberShader
Removed unused flag FLAG_FLIP_UVS

More to come ...
Added sprite color attribute
Enabled new shader flags
Added support for billboads

Improved ForwardRenderTechnique code
Fixed cubemaps rendering (Skyboxes)
Removed useless enum
Added Quaternion::Normalize static method
Fixed global math include
Improved SparsePtr class

Added implicit conversion from a normal pointer to a sparse pointer
Added implicit conversion to boolean
Added implicit conversion to normal pointer
Added support for const pointers
Renamed Get/Set to GetPtr/SetPtr
Updated Freetype

Added 64bits MinGW binairies
Fixed PCX loader crash
Merge remote-tracking branch 'origin/master' into Particle-Update