mission feasibility checker: add check for waypoint altitude relative to home position altitude
mission feasibility checker: remove audio warning for waypoint below home altitude
mission feasibility checker: add missing default return in checkHomePositionAltitude
Port expander driver first hacky version
position_estimator_inav: remove acceleration from state and INAV_W_XXX_ACC parameters, more NaN checks
ekf_att_pos_estimator: Default printing to off
mavlink mission item takeoff: read correct param for minimal pitch
Merge pull request #1013 from PX4/waypointminpitch

mavlink mission item takeoff: read correct param for minimal pitch
romfs: Added back mixer readme, now gets filtered out
Merge branch 'master' of github.com:PX4/Firmware
FMUv1 board prettifying
Enable SPI4 for FMUv2
Add SPI4 init bits for FMUv2
Fix SPI select on port 4 to use the right defines
Count devices on SPI4 / EXT from 1 as for the other buses
Merge pull request #1017 from PX4/spi4_support

SPI4 support
Updated AR.Drone parameters

Flight tested May 7th, 2014.
Merge pull request #694 from thomasgubler/beta_homealtitudewarning

mission feasibility checker: add warning if waypoint is below home altitude
Merge pull request #1019 from PX4/beta

mission feasibility checker: add warning if waypoint is below home altitude
Increase UART1 & UART5 RX&Tx buffer sizes

To fix MAVLink message garbling problems.