Added dynamic updating of BufferGeometry. Added BufferGeometry.applyMatrix. Added Matrix4.multiplyVector3Array.

CTMLoader now keeps references to typed arrays used to initialize GL buffers. These are later on deleted in WebGLRenderer (by default, if BufferGeometry.dynamic flag is not set).

Fixes #2166

(this commit should go to `unflipped` branch, it assumes straightforward UVs)