Modified garrison/taskDefend
New:
* treshold variables for taskDefend/createGarrison are now percentage (of bpos to be filled in building)
* treshold can be parsed as optional parameter to createGarrison (before class-array)

Code:
* code optimization for enterBuilding
* removed setVariable "ws_occupied"
* new setVariable: "ws_bposLeft" (array of bpos not occupied)
* changed setVariable "ws_bpos" (array of all bpos for building)