0.8.5a1 - Project structure

The toolkit has been overhauled to use a project hierachy. Projects
contain Levels which contain Areas. The Area-editing functionality is
entirely identical to the functionality before the new project
structure.

The Tab bar is replaced by a "Project View" widget. The Project itself
automatically handles loading and unloading Levels to remain
memory-efficient. There is currently no front-end GUI for creating new
Projects, opening Projects, adding Levels, or adding Areas.

Will be merged once the GUI is more functional.
0.8.7a3 - Enable map editing, fixes

Map editing is enabled and has been optimized when switching between
areas and levels. Added a save indicator to the Project view (the '*'
represents a changed area). "New Area" now saves the area automatically.
Bug fixes throughout.
0.8.7a4 - Tile Selection on Change Level

Fix a bug where the selection would not be redrawn when switching to an
empty level