BSSReader now reads constants and variables.

This lets the map editor do cool things.
Fix the map editor.

The map editor can now be invoked in ipython:
	import extras.pokemontools.map_editor as ed
	app = ed.init()
Then <app> can be modified on the fly to make up for lacking functionality.
Also see app.map.crop().

Now works with all maps in both Red and Crystal.

The version defaults to Crystal. To use with pokered, invoke from the command line:
	python extras/pokemontools/map_editor.py red

Or in ipython:
	import extras.pokemontools.map_editor as ed
	app = ed.init(version='red')

Also displays connections, but they're unaligned.
Merge remote-tracking branch 'origin/master' into fix-map-editor
map_editor: Fix automatic graphics decompression.
Merge pull request #83 from yenatch/fix-map-editor

Fix the map editor.