If an avatar TP's away (or quits), he will not
disappear anymore from a frozen scene. Unfreezing
makes him disappear of course (and clean up).
Known bug: if during Freeze Time mode someone
TPs away and then back, then he becomes a cloud
after Freeze Time is ended, which can only be
reset by another teleport (or relog) from either
the cloud or the one seeing him as cloud.
I decided not to fix this, cause there are things
with a higher priority and this - if it happens
at all - is rare and easy to recognize and work
around.
