Trigger special :_initialize_ event on startup.

See README for details.
Remove Queue class; move behaviour into Interface.
Make #method_missing private.
Add 'clear_line' escape sequence;

It resets the colours before clearing the line.
Extract Foreground and Background classes.
Fix up some tests.
Write log to "~/.vedeu/vedeu.log".
Add placeholder code for terminals which are too small.
Write error directly to STDOUT in this scenario.
Inline foreground/background code into ColourTranslator.
Rename some classes, reorganise:

- Add width and height to delegated geometry attributes.
- InterfaceCollection no longer mutates the stored interface.
- Move support/events to api/events.
- Move support/interface_store to api/store (Rename from InterfaceStore to just Store).
- Move ClearInterface to Clear.
- Move output/colour_translator to models/attributes/colour_translator.
- Move RenderInterface to Render.
- Remove TextAdaptor.
- Move API methods into respective classes.
- Add Vedeu.use API method to allow client to get interface attributes (useful when constructing interfaces).
- Add Vedeu.render API method.
- Deprecate Vedeu.run in favour of Vedeu.trigger for events.
Create 'screen_init' and 'screen_exit' convenience sequences.
Tidy up delegated methods.
Misc tidy up.

Make method_missing private, remove :nocov: markers, remove unused methods.
Tidy up logic here.
Add --debug flag for client applications.
Use API to create interfaces!
Make attributes an optional argument.
No longer need to process strings since we have the View API.
Remove dead tests.