Bugfix - FlyingF3: PWM6 and PWM7 used wrong AF

They bothed used AF2 which is unused for these pins
instead of AF1 so the PWM functionality wasn't
working.

Fixes #449
Revert "Merge pull request #555 from lilvinz/revert_533"

This reverts commit 49d4961ef622ef6095bac5b8d9635c87b708a5ab, reversing
changes made to a9ee62b4b09ce938c19e78b1508b5871510a14af.
Ground/GCSControl initialize gcsReceiverTimer to null
GcsControlGadget: formatting fix from review
Telemetry scheduler: Disables selection of first two columns.
Telemetry scheduler: add "ms" and "B/s" to non-empty cells.
Telemetry scheduler: Made first two columns selectable, but not editable.
Telemetry scheduler: Changed header names.
GCS-Fixed several runtime warnings and too verbose debug output
GCS Cleaned all GCS compile warnings
PiOS CAN: initial commit of stubs

This provides a minimal architecture for a PiOS CAN interface
to be used by PiOS COM.

There are a lot of limitations to using this approach.  CAN is a
multiple master multiple slave network and PIOS_COM (especially for
UAVTalk) is designed for point-to-point.
PiOS CAN: write an exposed SendData method for testing
PIOS_CAN: tweak cfg structure and add to pios.h
FlyingF3: enable CAN port
PIOS CAN: enable loopback testing and verify test messages received

This test works and it gets the same data back it sent.  The pins do
not, however, show any activity.
FlyingF3 Can Debugging: system task spews can message
Can FlyingF3: Use PD/1 instead of PB8/9

PB8/9 are used for PWM output
PiOS CAN: switch to interrupt driven system

This should also get the PIOS_COM interface working.  Messages
are filtered and received by FIFO1 now.
Sparky: enable CAN interface
FlyingF3: enable pios_com interface to pios_can