Inlined the vector math in BoundingBox.CreateMerged().
Fixed some BoundingBox methods to make the ref versions faster.
Inlined Vector3.Equals() for less method call overhead.
Fixed duplicate code in Matrix, now non-ref methods call the ref methods.
Merge branch 'develop' into math_opt
Merge pull request #1975 from SickheadGames/math_opt

Math Optimizations & Cleanups