Each channel was previously tracking a separate driver.
Now, channels are grouped within a channel group to save
RAM used for tracking and to better reflect how channels
are actually mapped.
This is a port of a work-in-progress by Sambas onto
the new driver infrastructure needed for boot-time
configuration.
PPM and PWM still don't coexist in a build but this
is closer.
All receivers now fall under the same driver API provided
by pios_rcvr.c.
This is part of a larger sequence of commits that will
switch the receiver selection over to boot time dynamic
configuration via UAVObjects.
priority preempts) and adjusting the priorities around to be more sensible.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@2355 ebee16cc-31ac-478f-84a7-5cbb03baadba
