Copter: throttle deadzone parameter

Allows increasing or decreasing the deadband size in AltHold, Loiter,
PosHold flight modes
Plane: don't use ground steering until flare in landing

we need to be able to guide the plane fully in the landing approach
Plane: added TKOFF_FLAP_PCNT and LAND_FLAP_PERCENT

easier control of flaps for takeoff and landing
Plane: added FLAP_SLEWRATE parameter

makes for smoother transition of flaps
AP_TECS: bring in flare sink rate more slowly

this should reduce pitch overshoot in the flare
AP_TECS: allow zero throttle in flare for landing
Plane: allow zero throttle in LAND_STAGE_FINAL
Plane: only override takeoff/land flaps if non-zero
Plane: raise the default WP radius

with L1 a large radius doesn't mean it turns too early
Copter: restore CLI set parameter feature

Added back the ability to set params from CLI
Copter: default LAND_REPOSITION to 1
AP_HAL_VRBRAIN: added management for external relay 1 and 2
AP_relay: added default relay pin for VRBRAIN
VRBRAIN: added startup of internal mag's driver for VR Brain Standard 5
AP_HAL: VRBRAIN corrected EEPROM size and added terrain folder on MicroSD
AP_HAL_VRBRAIN: enable 2nd GPS for VRBRAIN 5
Build: VRBRAIN corrected order of MAG startup
Build: VRBRAIN corrected order of MAG startup for 4.5 board
Copter: AC3.2-rc6 release notes
Copter: update AC3.2-rc6 release notes

Forgot to add GPS driver buffer overflow item