cleaned up CL_SendMove a lot, added notes on number of bytes used for different protocols

cleaned up CL_SendMove a lot, added notes on number of bytes used for different protocols
made CL_SendMove never send a clc_ackframe for frame 0 in any latestframenums slots
made CL_SendMove discard only the clc_move portion of the first two messages (the ones dropped to avoid input leftover from the previous level), still sending the clc_ackframe message
changed CL_SendMove to not accumulate move messages but just send the latest (may improve cursor issues in prydon gate using non-clientcursor mode)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@4813 d7cf8633-e32d-0410-b094-e92efae38249