Update some comments in the LZP3 implementation.
Check in my TODO file for DMC.

Maybe I'll be interested in hacking on this more someday... but there
are other more promising algorithms at the moment.
Rename Lzjb -> LzjbR to reflect the changes we've made to the algorithm.
Add unmodified LZJB algorithm.
Describe the various algorithms implemented.
Improve modelling in LZJB-R.

Use a context-1 model when we need to encode literals; use a log-length
model when we need to encode match length and position; special case
"offset same as before" (used for "match with gaps").
Update benchmark results for LZJB / LZJB-R.

Improved modelling made LZJB-R smaller w/o making it slower.
The new LZJB is wicked fast, but not so small.