Big push on getting the docs cleaned up before 1.0. Proper wrapping of
everything so it's decently viewable from the command line (or as
decently viewable as markdown can be - the tables will never look great
from the command line).
Only one code change in this PR: rename bouncetime to bounce_time
(everything else is PEP-8, so this probably should be too) and change
its units to seconds from milliseconds (again, all other durations in
the library are in seconds, so it feels inconsistent that this one
isn't; for the sake of those who won't read the docs - which is most
people - I figure consistency helps with guessing!).
Permit devices to be explicitly closed and used as context managers.
Also deal with cleanup properly at script end and ensure objects don't
step on the global cleanup function.
Add a nice __repr__ to the GPIODevice base class.
This isn't much but generally I think `__repr__` implementations should
be deliberately simple: firstly, they're frequently used for debugging
so if they're at all complex you risk making a debugging tool buggy
(very annoying!). Secondly, if you pour too much info into them you risk
making the debugging output cluttered, so I tend to prefer keeping it to
straight-forward simple to retrieve/calculate info without excessive
detail (if the user wants more, they can always query it directly).
There is one refinement here: in SmoothedInputDevice, `__repr__` is
tweaked to ensure that when partial is False (the default), and the
queue isn't filled, `__repr__` doesn't block (because it should *never*
block).
