#20 Obj: sometimes invalid model with OptimizeMeshes

[Kim Kulling]

The first one is with aiProcess_OptimizeMeshes. When using
aiProcessPreset_TargetRealtime_MaxQuality , on an obj model, the mesh is corrupted.
When using aiProcessPreset_TargetRealtime_Quality | aiProcess_FindInstances
| aiProcess_ValidateDataStructure (everything but aiProcess_OptimizeMeshes),
the mesh loads fine. Also, when loading the same model in 3ds format, the model
loads fine with aiProcess_OptimizeMeshes. The structure of the obj file is different
from the conversion, but it is the same triangles.

[Kim Kulling]

Is this issue still occurs?