* Added optional GPU skinning
* Added skinned bone matrices support for different file formats.
* Moved new shader locations to end of enum to avoid breaking existing examples. Added gpu skinning on drawing of instanced meshes.
* Added GPU skinning example.
* Removed variable declaration to avoid shadowing warning.
When using FormatText() several times in same function, returned string is static and so, the same is returned, resulting in failures on shader loading.
Issue was related to vertex tangent attibutes not uploaded to GPU, a quick solution was implemented for new vertex attributes loading for already existing meshes... I don't like it specially but it will work for now.