AP_Math: Comments on WGS coordinate conversions
AP_NOTIFY: RTK GPS visual notification through faster blink
SITL: Piksi Heartbeat Message support, Integer-RTK baseline simulation
AP_GPS: SwiftNav RTK Driver and GPS AutoSwitch param
ArduCopter: GPS Callback for calculating base position
MAVLink: New message definitions for GPS_RTK
GCS_MAVLink: Add support for GPS_RTK messages
AP_GPS: GPS calculates MAVLink messages for GPS and GPS_RTK
ArduCopter: Move MAVLink size check into library
GCS_MAVLink: regenerate headers
GCS_MAVLink: fixed flymaple build

has dual GPS but no RTK support
AP_GPS: fixed build errors and warnings in SBP driver

shadowed variables and implied casts in structures