UpdateModelAnimationBones() is deprecated

[execphantasmagoria]

Overview

A few things were added and a few things need fixing. Namely, in Raylib V6, MatrixMultiplyValue() was added. Secondly, current UpdateModelAnimationBones() is deprecated in favour of UpdateModelAnimationsEx(), yet UpdateBones() exists as a method for ModelAnimation class and uses UpdateModelAnimation as a stand-in function. Lastly, Unload() of ModelAnimation always unloads one animation so no need of animCount.

Recommended fixes

• Deprecate UpdateBones() and replace with BlendPose()
• Polymorphically unload 1 animation unless argument is provided.
• Add the MatrixMultiplyValue() functions. Add in MatrixIdentity later when it is used anywhere.