fixed bug that allowed accidental speed cheating with cl_movement 1 mode (move->time...

fixed bug that allowed accidental speed cheating with cl_movement 1 mode (move->time was being cleared by ApplyClientMove, so when ReadClientMove calculated how much to move since the last move, it always thought the last move was at time == 0, and then it clamped this delta to 0.1 or less, which prevented it from being completely ridiculous, but still horrible)
added kicking of speed cheaters (if they echo a timestamp that has not yet been issued by the server, they're clearly lying)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5988 d7cf8633-e32d-0410-b094-e92efae38249