SCE_Geometry_ComputeNormals(): dont normalize null vectors
QEM decimator: FixInversion() is more sensible, so to speak
Voxels: material support
Added a bunch of useful fonctions for the SCEVoxelOctree module
Added SCE_VWorld_SetCreateTrees() function
SCE_Grid_FillupZeros() made public
QEM decimator: basic normal support
QEM decimator: added naive infinite-loop check