AP_GPS: Removed CFG-DAT message from 3DR-Ublox-NEO7

CFG-DAT is generated by U-Center but no longer used by the receiver.
Frame_params: 3DR_Iris+
Decreased ATC_RATE_RP_MAX to 18000
AP_AHRS: added get_yaw_rate_earth()

used to estimate course correction on takeoff
Plane: make auto takeoff independent of compass

this solves a problem of poor initial yaw due to poor compass offsets
causing a takeoff to not be in the direction the plane is pointing. A
summed gyro is used until the GPS speed is above 5m/s for 2 seconds,
then the GPS heading corrected by the summed gyro error is used for L1
based navigation for the rest of the takeoff
Frame_params: Adding 3DR_X8-M_RTF.param
Frame_params: Updating 3DR_X8-M_RTF.param