Generals can be deployed with the new requisition

Many other changes other than the new requisition resource:
* Areas now use the battleground as basic variable, but can get the
general if they need some information from him.
* New teleport method for entities.
* Minions and generals got the side and (x,y) parameters order
swapped. (x,y) parameters are now optional always.
* Last change not yet applied on Entity and other subclasses. This
is so confusing right now, I think.
* render_bar() properly moved to window.py