AP_GPS: fixed GPS time in HIL

account for 10 year difference in epoch between unix time and GPS time
Frame_params: Updated Iris with 3 Position Mode Switch
AP_GPS: added GPS_SBAS_MODE parameter

allows SBAS to be enabled/disabled
AP_GPS: added GPS_MIN_ELEV parameter

allows setting of satellite elevation mask in degrees
Copter: add short delay to arming to allow RC input

The short delay gives time for the RC inputs to be processed which
removes the chance of a false-positive on the "late frame" radio check.
A false positive could lead to an immediate disarm right after arming.
Copter: land check gets overall throttle and rotation rate check

add check that overall throttle level is below the non-takeoff throttle
instead of just checking that it's motors have hit their lower limits
because low limits can also be caused by high yaw rotation requests.
Absolute climb rate requirement reduced to 30cm/s
Copter: pre-arm consistency check of gyros
Cotper: AC3.2-rc7 release notes
AP_Relay: added RELAY_DEFAULT parameter

this is useful when using a Pixhawk with an external relay, as it
allows you to cope with the pullup on the PWM pins
Copter: minor ReleaseNotes format change

This also helps to kick off the build of AC3.2-rc7
Frame_parameters: Updated Iris with 3 Position Mode Switch
Copter: reduce alt hold defaults

Throttle Rate P to 5.0 (was 6.0)
Throttle Accel P to 0.5 (was 0.75)
Throttle Accel I to 1.0 (was 1.5)
Frame_Params: Added 3DR Iris+
TradHeli: update AttControl params to match multicopters
Copter: increase EKF_CHECK_THRESH default to 0.8

Also remove unused #define related to inertial nav check (now removed)
Initial Commit
CHDK-Scripts: adding README.md
CHDK-Scripts: Adding kap_uav
DataFlash: allow use of a smaller writebuf for PX4v1

this fixes logging on PX4v1
Frame_params: Updated 3DR_Iris+.param