[Fixes #381] Replaces GPU Skinning for Animation Blending

[execphantasmagoria]

This series of commits do three things:

• Updates the Matrix Multiply() and Matrix operator*() to polymorphically use the new MatrixMultiplyValue() when passed in a float argument.
• Unload() now unloads one animation by default, unless provided an argument count.
• UpdateBones() is replaced with Blend() to reflect new animation mechanism.

[execphantasmagoria]

It shouldn't have any more build errors.

[RobLoach]

There's an int* animCount that's returned when calling LoadModelAnimations(). Would there be a way for us to leverage that so that we don't have to worry about unloading 1 when there could be 10?

[execphantasmagoria]

In order to use the populated int* animCount, we would have to make the Load() function a non-static method, such that it can store the object's animCount in an attribute and use in while unloading.

however, making it so requires a ModelAnimation object to call load, that may defeat the design philosphy of raylib. I will try to think of a workaround. The current workaround for this would be to use function overloading. Have the Unload() optionally accept an animCount. This assumes the programmer knows how many animations are loaded.

[RobLoach]

Hmmm, that is a challenge. Surprised it's not kept in the ModelAnimation struct itself.

[execphantasmagoria]

After talking to raysan, it is my understanding that UnloadModelAnimations() is meant to unload an array of animations, and a ModelAnimation object would only have 1. In that case, i believe there should a UnloadAnimations(int animCount) static method can be called with an array of animations, along with Unload() to unload the animation data of the object that calls it.

I have implemented the same.