Updated prop_bonus_round.sp

Added ability to force props to move at a specified speed.
Updated prop_bonus_round.sp

Rearranged code, updated activity display on sm_prop when acting on
multiple players.
Updated prop_bonus_round.sp

Removed global variable g_iPlayerModelIndex[], as it was only used when
telling the propped player which prop they were turned into. In place of
it, PropPlayer now returns the index value of the prop selected.