List of things to complete for lossless codec:

* How to deal with data_precision vs. BITS_PER_JSAMPLE for compression codec.

* Re-visit use of insufficient_data - see jdhuff.c and jdlhuff.c.

* How to check BITS_PER_JSAMPLE for lossy mode (ie, 16-bit data)? -
  see jdinput.c.

* Check comment blocks for errors/changes.

* Review new filenames.  Try to avoid filename conflicts with possible JPEG-LS
  codec.