Add support for a decompression mask

[nfrechette]

When Decoder.decompressTracks(..) is called, we decompress every single track and for QVV tracks it means each rotation/translation/scale. However, animations often have tracks that do not move. With ThreeJS in particular, we can query which rot/trans/scale is needed and we could build a mask to control which ones are decompressed. This would speed up decompression a bit by avoiding reading/writing of unnecessary data as well as interpolating it.