Add a (half-finished) input library, that for now simply allows
registration and triggering of events.
As next steps, the trigger will happen as part of a separate thread that
reads input events.
Additionally, invoking commands via a execute() will be supported.
Thirdly, there is need of a way to selectively update the affected
modules (widgets), which should be possible given that the event
contains both the instance (widget ID) and name (module name).
Add modules to show date, time and date and time. Instead of introducing
a "fancy" aliasing mechanism, simply implement time and date in terms of
datetime, by inheriting and overwriting selectively.
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.
Add logic for parsing commandline options, and a preliminary stub for
loading modules.
Note: The idea is that core.module.load() will return a valid, but
empty, module that displays an error, if the module cannot be loaded
