Command stacking

Setting rally points for buildings
Fixed potential crash in distanceToResource()
Fixed selection box functions going out of scope
Fixed create villager and create swordsman button
Allows stacking of commands by holding down the shit key:

A list of actions for a given actor is now generated if the order is given while holding down the Shift button
Execute list of stacked commands in order for a given actor
Show flags for stacked order targets for a given actor if the actor is selected and the actor is owned by the player