APM: make wind direction message clearer
checksum: make it possible to have a board specific CRC

This allows for assembler optimised CRC routines on systems that have
one, such as AVR. On an AVR2560 this speeds up the CRC by a factor of 2.
helpers: fixed a const warning
Added helper functions
Merge branch 'master' of github.com:mavlink/mavlink
Added Omnidirectional flow message
Mavutil: add ArduCopter arm/disarm commands
pymavlink: show differences between two parameter files
Message Definitions: add MAV_AUTOPILOT_SMACCMPILOT to MAV_AUTOPILOT enum
Message Definitions: change smaccmpilot description to URL
magfit: fixed a problem with outliers in data
flighttime: show percent in log
mavextra: useful functions for motor mag field fitting
magfit_motors: initial cut at fitting mag field with motor influence
Merge pull request #89 from GaloisInc/master

thanks Pat!
Added new 'CS' option to mavgen.py

.Net assembly generation
Fixed bug with packet sequence number incrementing
generator: error_limit is an integer
Added missing datatypes to param_union in mavlink_types.h for v1.0
Improved phrasing of notice that validation step is skipped.

Conflicts:
	pymavlink/generator/mavgen.py