When touched by player or damaged fades away.

-destroy_time:  how long it takes to fade away once it has been touched

-fade_to: how much platform fades out. 0-255  0 is completely invisible.

-drop: if true platform will shake and fall after destroy time.  platform will not 
fade or repair if set.

-disappear: platform will disappear after destroy time.

-repair_time: time before platform starts to fade back in.  If less than or 
equal to 0 platform never repairs itself.