Add initial structure for decompressing JPEG XR images (assist #8493).

This PR adds a Bio-Formats module named ``ome-jxr``. This module implements part of the ITU-T T.832 recommendation for "Still-image compression – JPEG XR". The main blocker encountered during work on the business logic was the lack of proper bit-level stream readers in Java (and Bio-Formats). The code implements the specification up to point 8.4.22.6. Comments have been left in places where the requirement of an enum or class was unknown before the decompression stage.

For discussion during code review:
- the ITU-T spec mentions global variables and codestream-level variables. I think a globally visible store of variables needed during the decompression process would make the code cleaner (reduced number of private class members),
- class hierarchy,
- test coverage and construction.