fixed several issues in the recent effect rate limiting code (situations

fixed several issues in the recent effect rate limiting code (situations
where it could get stuck and stop sending them entirely due to too low a
rate setting)
fixed issues introduced in recent stats code (was not resetting them on
a level change, leading to very broken stats for the client)
this includes a missing part of the LOWPRECISION-on-all-entities patch so
that now works

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@7107 d7cf8633-e32d-0410-b094-e92efae38249