New features, performance improvements, bug fixes:
- Added return route to lobby for fast food customers when leaving. [FastFood.cpp]
- Check for FastFood customer arrival via priority_queue. Set journey only if route is not empty. [FastFood.cpp]
- Check if FastFood customer is ready to leave via ordered list. Skip customer if route to leave is empty. [FastFood.cpp]
- Update all routes only when elevator shaft has been resized, and only when bulldozing a transport item. [Game.cpp]
- Update all routes only when constructing a transport item, otherwise just update route of newly constructed item. [Game.cpp]
- Tidied up code to prevent construction when clicking on in-game tool windows. [Game.cpp]

Bugfixes
--------
- Only consider checking the score of the newly found route if it is not empty. [Game.cpp]
- Elevator serves only up till the floor below motor assembly. [Elevator.cpp]
- Call correct desc() function for Rect description() [Rect.h]