Add Servo and AngularServo implementation along with docs and tests.
This is a deliberately minimal implementation designed to be added to as
we agree on new extensions (better than making an all-singing,
all-dancing version in which I get things wrong and then wind up making
backward incompatible changes to get it right :)
In particular the `pi_revision` thing in PiGPIOPin, all the stuff @lurch
picked up in `pins/data.py` (thank goodness *someone's* watching!), and
make all those links pointing to "Notes" point somewhere useful like
"Pin Numbering"...
Tweak the second keyboard robot recipe so it detects keyboards and
doesn't throw exceptions on unknown keys. Also add a note to the recipe
that it won't work over remote connections like SSH.
Overhaul the pi_info system:
Pin factories are now capable of generating pi_info themselves (although
currently they all just look up the revision and call pi_info with a
specific one).
PiGPIOPin will now return pi_info for the remote pi which can be
specified by parameter or implicitly by the environment vars.
Overvolted Pis should work properly no matter what (some argument over
whether the revision 7 or 8 chars in this case; both should work). Added
some minor tweaks for the new camera-capable Pi Zero
Finally, added a bunch of tests for pins.data
Adds a keyboard controlled robot recipe that uses curses. Advantage is
that no external deps are required, disadvantages are that it'll only
work from a terminal (or terminal window, basically not IDLE).
While the tests work well on a PC or Travis, the Pi (where I ought to be
running them!) has some issues with the timing tests. Need to relax the
tolerance of the "assert_states_and_times" method to 0.05 seconds
otherwise it periodically fails even on something reasonably quick like
a Pi 2 (less failures on a Pi 3 but still occasionally).
Also reduced default fps to 25; if the default timing occasionally fails
on a Pi 2 it's evidently too fast for a Pi 1 and shouldn't be the
default; 25 also doesn't look any different to me on a pulsing LED.
There's also a bunch of miscellaneous fixes in here; last minute typos
and chart re-gens for the 1.2 release.
