make it possible to toggle the display state of a widget between
"displayed" and "minimized" also for modules that re-create their
widgets during each iteration.
see #661
by default, allow toggling the minimized state of a widget via the
middle mouse and draw a single unicode char instead of the actual
widget, maintaining all states.
fixes#661
a module can now set `self.background = True` in its `__init__()` method
to make sure its update method is invoked in a separate thread.
also, do a PoC implementation of this for the github module.
TODO: add this to dev doc
see #640
OK - so I have to admit I *hate* the fact that PIP seems to require a
subdirectory named like the library.
But since the PIP package is something really nifty to have (thanks to
@tony again!!!), I updated the codebase to hopefully conform with what
PIP expects. Testruns so far look promising...
