added ms5611 driver
refactored pressure sensor subsystem to allow multiple sensors
couple changes in PWM driver to make motor/servo arrangement for airplane mode more intuitive
moved MAX_MOTORS/MAX_SERVOS etc into drv_pwm.h
staring to merge back in airplane/flyingwing mixes
fix for tri servo display - mwc moved it to servo[5] again, gui was broken, function not.
will probably implement custom mixer soon (motors only, no servos)
git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@198 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61
