Fix telemetry radio RSSI calculation for SI1000 based modems

New item uses altitude from last item

Redesigned setup buttons to save space

Explicit raw/cooked values for Facts

Add virtual joystick setting.

Also reflow settings pane to take less space

Remove MavCmdPreflightStorageCapability

README.md: Explain why Qt distro packages can't be used

Reflow flight mode layout even when joystick control is enabled

Mission Item raw/friendly edit support, plus more [merge after Stable 2.8]

Auto connect support [merge after Stable 2.8]

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients

travis-ci ubuntu trusty

Also friendly editor for MAV_CMD_NAV_ROI and MAV_CMD_DO_SET_SERVO