Allow custom builds to turn off firmware version check

Q_ENUMS is deprecated and should not be usued.
Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Create new, specific button for clearing mission from vehicle
Adjust sizing of DropPanel

Allow plugins to define a left placement for its custom flight widget.
When placed on the left, the action tool strip is placed on the right side.

Eliminated flight widget "states"
Define flight widget top margin (plugin options)

Also added insert pattern support to hamburger

Added top/bottom alignment state to map scale
Allow disabling instrument widget altogether
Added an otherwise redundant row to PlanToolbar so it matches the same button position as the main toolbar
Fixed typo (Math.max()) in ScreenTools
Fixed Javascript Exception in OfflineMap
Increased the import window size in OfflineMap
Added function to MainWindow to disable toolbar for a truly modal dialog
Added code so clicking on an open toolbar indicator will cause it to close

Remove showSensorCalibrationOrient

Replaced by new settings capability

These are covered by SettingsGroups now

Allow plugin to define default font size, toolbar height and option to display/hide plan view selector.

Made QGCCorePlugin derive from QGCToolBox and expose everything through the same mechanism as everything else.