fixed global votes being cleared when changing team between red<->blue
Cleaned up CL_SendPureChecksums, no longer need to do this special Yf -> cp stuff since code is available.
Moved changelog to CHANGELOG.txt, added developer notes to README.md
Batch of client serverbrowser fixes merged from ioq3.  MPlayer mostly removed.  Servercache still loads it for legacy files (for now).