New Area Viewer and many corrections

- implemented a new area viewer from scratch, featuring
  - switch between day/night WEDs
  - switch between opened/closed state of doors
  - enable/disable different item layers (e.g. actors, triggers, doors)
  - item-specific information on click and mouse over
- many corrections related to the new area viewer
- all duplicate resource entries have been numbered for easier external
access
- new field added to infinity.resource.wed.Tilemap