AP_Math: fixed build of vectorN class on PX4
AP_HAL: added HAL_CPU_CLASS define for selecting algorithms

this will make it easier to select the appropiate level of algorithm
for a CPU
AP_Baro: use HAL_CPU_CLASS in baro driver
DataFlash: use HAL_OS_POSIX_IO
HAL_Linux: fixed build
Plane: default LOG_BITMASK to 32767 on non-APM
HAL_PX4: removed code which drops throttle to 900 on loss of RC

rely on vehicle code checking for last data coming in
px4: enable dual telemetry by default on FMUv1

this makes us compatible with wiring diagrams from PX4 site
Plane: fixed redundent logging
HAL_PX4: fixed RCInput race condition

the number of channels could be zero with thread switch at the wrong
time
AP_NavEKF: Inertial Navigation Code - 24 State EKF

initial version converted from matlab
AP_NavEKF: Updated GPS input processing
AP_NavEKF: Updated measurement fusion control
AP_NavEKF: Corrected height update timeout error
AP_NavEKF: Added constructor for measurements
AP_NavEKF: Updated measurement references
AP_NavEKF: fixed build for APM environment
Plane: added NavEKF object
AP_NavEKF: Explicitly defined numerical constants as single precision using f suffix
AP_NavEKF: Updated comments in header file