Avoid using initialialised pointer in sonar interrupt handler.
CC3D - Change the default alignment of the board to match the default
open pilot alignment.

This makes it easier for new users to adopt cleanflight without having
to look up the alignment cli settings or rotate their boards in their
existing aircraft.

See discussion here:

http://forums.openpilot.org/topic/43569-baseflightcleanflight-ported-to-cc3d/?p=360886
Bugfix when using sonar as well as rx-parallel-pwm

This allows sonar to be used at the same time as parallel PWM for the receiver.  If the RX_PARALLEL_PWM feature is enabled, then the sonar system uses motor ports 5 and 6, otherwise it uses receiver pins 7 and 8.
Cleanup sonar support for Naze/Flip32/Olimexino.  Add Sonar
documentation.
Mention Flip32+ in sonar docs.
OLIMEXINO - Document shield sonar port pinout.