Added SYNC_DEBUG so sync debugging doesn't clog stdout

Fixed a problem with loading actors in savegames that cropped up when
targeting/shooting

Don't clear player->message when loading
Added a simple logging module
Use an obuf_t instead of a cbuf_t in d_log

Add some descriptions to obuf_t and cbuf_t

Turn on sync debugging, back to the grind :)
Removed netpeer_t.last_command_run

Added netticcmd_t.index

Updated TODO.md
Refactored netpeer_t's sync members into netsync_t

Fixed a bug in m_obuf that wasn't NULLing new object slots; fixes
closing logs during exit
Rebuilt tags
Sync 90% there; still a little jittery but close

Got rid of N_Update, after I found an errant call to it

Added a M_CBufPop function

Moved commands onto indexing

Fix a problem in player serialization where weapon states weren't fully
serialized
Sync finished

Next up: disentangling command processing from P_PlayerThink and
P_MobjThinker