Player commands
---------------
+ai
+Do what the AI would do.
+
wait
Make player character wait one turn.
Set part of selected thing's memory of the game map to string argument: the line
of the argument's number.
+T_MEMTHING [0 to 255] [0 to 255] [0 to 255]
+Add to selected thing's memory of things on map thing of ID of first argument,
+y position of second argument and x position of third argument.
+
TT_ID [-32768 to 32767]
Select thing type to manipulate by argument as ID. If argument is <0 or <255,
change it to the lowest unused thing type ID. If thing type of ID does not exist