Also re-numbers energenie sockets 1-4 (as noted by @bennuttall in
comments to #239), and adds several "real pins" tests and board tests.
The bad-PWM stuff is currently disabled as it causes segfaults when
running the tests and I can't seem to trace the cause at the moment.
Finally, I've tweaked the deb config to suggest gpiozero, removed spidev
as a mandatory dep (which'll fix installs on wheezy for py3), and
there's some more miscellaneous last-minute stuff here that I can't
recall...
This PR adds a software SPI implementation. Firstly this removes the
absolute necessity for spidev (#140), which also means when it's not
present things still work (effectively fixes#185), and also enables any
four pins to be used for SPI devices (which don't require the hardware
implementation).
The software implementation is simplistic but still supports clock
polarity and phase, select-high, and variable bits per word. However it
doesn't allow precise speeds to be implemented because it just wibbles
the clock as fast as it can (which being pure Python isn't actually that
fast).
Finally, because this PR involves creating a framework for "shared"
devices (like SPI devices with multiple channels), it made sense to bung
Energenie (#69) in as wells as this is a really simple shared device.
