mirroring: initial commit

This adds support for mirroring depth and video streams.  There are two caveats:
* The IR stream cannot be mirrored in hardware since doing so corrupts the stream.
* Video stream is of lower quality because the Bayer decoder assumes a GB interleave but a mirrored stream has a BG interleave.


Signed-off-by: Benn Snyder <benn.snyder@gmail.com>