Also fixed some code in QGCPX4VehicleConfig to remove unnecessary DialogBare references.

Added documentation and clarified messages to the user.

This feature can be enabled at compile-time and documentation has been added to the README.

Now properly checks for if QUpgrade submodule has been cloned.
Allows for disabled QUpgrade compilation.
Altered some code so that compiling without the QUpgrade module could
succeed.
Updated README about QUpgrade submodule.

PX4 config: Remove the specialized throttle handling - this needs testing, but doing the math on paper it doesn’t look like a special case is needed / wanted here.

Use the reversed values for the four control channels as well. Not using them would make the display very confusing.

Enable RC calibration mode during RC calibration to tell vehicle to ignore stick inputs for that period

TeamCity caught this, but I thought the error was from my warnings
work. Turns out it was a real build failure. Windows doesn’t know which
floating point floor to use. In reality the parentheses are in the
wrong place and should be the floor of the divide by 2. But integer
division is always floor, so it’s not needed at all.

Delete of last link would cause crash. Need to check for -1 which
signals no selection in combo box.

Fixing -Wuninitialized

Not sure what qmake # escape is. So fixed the problem instead.

Realized that I had configured my APM:Plane incorrectly since
FlightModeConfig was only set up to work with APM:Copter. Changed code
to respect mode switch channel parameter across all APM frame types.
Also a pile of other changes to make this code much more bullet proof
and correct. Implemented simple mode as well. Changed the style of the
code to be more data driven. This allows for adjusting for new param
values without needed to changing any code.

Realized that I had configured my APM:Plane incorrectly since
FlightModeConfig was only set up to work with APM:Copter. Changed code
to respect mode switch channel parameter across all APM frame types.
Also a pile of other changes to make this code much more bullet proof
and correct. Implemented simple mode as well. Changed the style of the
code to be more data driven. This allows for adjusting for new param
values without needed to changing any code.