The core.output module now manages the list of modules and retrieves the
widgets inside draw() itself. That way, details of drawing/updating
widgets are not visible from the outside anymore.
Add generic "draw()" method that redirects internally to the actual
calls. These can now produce JSON, which is nicer because:
1. Easier to use during testing
2. More flexible
3. Centralizes printing (somewhat)
Still, the "suffix" concept isn't really nice, but so far, I have no
better approach.
Experimental re-implementation of core functionality with the aim:
- Depend only on the Python Standard Library for core
- If modules are missing elsewhere, *never* throw
- Unit test *everything*
- Cleaner and more minimal implementation
- Better integration points for existing implementations (charts,
braille, etc.)
- Full backwards-compatibility with existing module system (except where
modules can be vastly simplified)
