improve serialization based on feedback: make it easier to serialize a single object, or single shape, or single bvh.
Modified Bullet/Demos/ConcaveDemo to use btSerializer to serialize the btOptimizedBvh (or optionally the trimesh+bvh)
You can also serialize trimesh without BVH, use:
serializer->setSerializationFlags(BT_SERIALIZE_NO_BVH);// or BT_SERIALIZE_NO_TRIANGLEINFOMAP
Note that BulletFileLoader is has no dependencies on BulletDynamics/BulletCollision.
Also added a custom build step to copy asset (.bullet and .obj file) into the executable folder
Made a few 'char*' 'const char*' to avoid compiler warnings
