use "realtime", not the float time global, for entity allocation and freeing to prote...

use "realtime", not the float time global, for entity allocation and freeing to protect the entity slot for 0.5 seconds (now 1 second). Should help entity networking a lot, as the time global doesn't grow monotonically when cl_movement is used on a client (basically, a client with 500ms latency can free an entity in PlayerPreThink, and that entity slot could get immediately reused in the next server frame or think function).

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@8891 d7cf8633-e32d-0410-b094-e92efae38249