Count only vertex groups with influence when exporting

[Brachi]

A behavior I noticed when applying armature parent with automatic weights to models is that all bones create an entry in the vertex groups for every mesh, even if the mesh is not influenced for the vertex group of the bone. When exporting RE5 models, it seems all vertex groups are used and hence the 32 bone limit per mesh is reached. When exporing, only the vertex groups that have a weight > 0 should be exported only.

[Brachi]

Fixed and merged.