Virtual joystick improvments

Add missing Radio Component trigger

New QGCFlickable control

- Positions are bounded to rectangle
- No longer re-centers if thumbs go outside bounds
- ThumbPad moves to meet first thumb position, this prevents
inadvertent movement as you put your thumb down

Add missing MockLink params

Prevent incorrect param binding while switching component id

Add scroll height indicators to Flickable

Stop paying attention to heartbeats while downloading logs.

Set initial size for log download.

Reboot message no longer needed

Clip parameter row strings

Since parameter system will pop message based on meta data

Joystick: Fix throttle center point.

Show ESP8266 Firmware Version in Summary Panel

The lines removed set the center point of the throttle axis to one extreme of the joystick range. This causes an offset value when the stick is centered if the joystick does not return exactly zero. This is important for vehicles with reversible throttle, such as ground robots or boats.

APM 3.2 support

Stop connection lost handling during accel cal

Move GCS heartbeat to MultiVehicleManager

Move connection lost handling to Vehicle

Fix more incorrect severity problems

Stupid proof Linux serial port use

APM Sensor: UI handles older firmwares