Merge remote-tracking branch 'upstream/mavlinksubmodule_joystickinput' into mavlinksubmodule_joystickinput

Conflicts:
	src/uas/UAS.cc

this adds an option to select the mode of the joystick in the joystick
config widget. The mode sets the setpoint type which is sent when moving
the joystick.

Conflicts:
	libs/mavlink/include/mavlink/v1.0

FGFS multicopter HIL

Google Maps fix

Fixes to botched Qwt 6.1 update

Update Qwt to 6.1

Fix linux release build warning

Plotting data now defaults to drawing a line with no symbols.

Qt5 fixes

I was unsure how to update the QwtPlotPrintFilter code, so I just commented it out with a FIXME.

We also document how we got the source code and keep our modifications out of the Qwt directory.