Version 2.15 - console variables for damage control and trigger touch control

• Fixed error messages in the error logs, about Get*ObserverTarget complaining about players being not in game.
• Added cvar redie_ghost_disable_triggers (by default disabled) to block activation of trigger_multiples (touch, starttouch and endtouch) by ghosts.
• Added redie_ghost_world_damage (by default 0) to enable or disable damage for ghosts by world elements (entities such as trigger_damage).
• Added redie_ghost_player_damage (by default 0) to enable or disable damage for ghosts by players (this only applys to knifes and grenades, projectile weapons are always blocked due to technical limitations).
• Added redie_ghost_fall_damage (by default 0) to enable or disable fall damage for ghosts.