px4fmu: added publication of input_rc ORB values

this allows for PPM input with no IO board
px4fmu: add support for write() interface for PWM output

this matches the PX4IO interface
appconfig: disable mathlib and associated examples on APM

these are far too large (777 kbyte) and we can't fit them with the
ArduCopter flight code
nshlib: added cmp command to nsh

this is useful for startup scripts testing for auto-upgrade of add-on 
board firmware
px4io: added INAIR_RESTART enable/disable flags

the autopilot code needs to know that in-air restart may happen, so it
should be something that is enabled, rather than on by default.
px4fmu: enable BINFS

needed for APM startup
px4fmu: disable a bunch of code when built for APM

this leaves us enough flash to fit APM
More sensible error handling in calibration
Merge branch 'master' of github.com:PX4/Firmware
px4io: fixed signals for lower latency PWM output

poll() is not interrupted by signals, whereas usleep() is
ms5611: try to measure the performance cost of I2C timeouts
Adjusted stack size for commander app
Switched I2C to interrupt driven mode
Merge branch 'master' of github.com:PX4/Firmware into px4io-i2c