Shortcuts

Just some additional keyboard shortcuts:
* TAB for cycling through visible enemies (= clicking "danger indicator")
* ENTER for picking up things and the like (= clicking hero's current position)
* H for displaying hero's stats
* J for displaying the Journal
* C for displaying the Catalogus (now it's handled in StatusPane, not in Toolbar)
Also a new static boolean field "modifier" was added to PDInputProcessor for easy checking if Control key is pressed. The implementation is not entirely correct, I'll try to fix it later. Ctrl+click can be used for changing an item in quickslot.