Controls respect QGCPalette settings. Also added test window.

Since this is generic Qml support not specific to FactSystem

Fixes Issue #1162

Changing the order of the QGCFileDialog::getSaveFileName() function. The idea was to expand the existing QFileDialog version but as we removed the selectedFilter, we might as well make this more intuitive. The options argument is the one trully optional and should be last.
Adding an example to the documentation on how to go about figuring out what file type was returned by these functions.

Removed the “selectedFilter” argument from the QGCFileDialog functions along with references to it in unit tests.
Fixed function declarations and prototypes formatting while at it.
Changed the caption of a few file save dialogs with a more descriptive text (explicitly telling what is being saved).

Remove erroneous use of QFileDialog::selectNameFilter(). No filters are to be selected. The argument selectedFilter is a pointer to a String to receive the filter selected/used by the user.

- Central widget no longer stacked. Views are added/removed to layout
to switch view
- Dock Widgets are globals with single instance of each type
- Both central views and dock widgets are just-in-time created saving
lots of memory

UAS may be around at constructor time

No need to force them to show

This way the dock doesn’t end up too wide

Tweaking the documentation for QFileDialog and replacing the doxygen "@" escape to be consistent with the rest of the code.

QGCApplication::saveTempFlightDataLogOnMainThread()
MainWindow::startVideoCapture()
QGCBaseParamWidget::saveParametersToFile()
QGCDataPlot2D::savePlot()
QGCDataPlot2D::saveCsvLog()
WaypointList::saveWaypoints()
QGCToolWidget::exportWidget()
LinechartWidget::startLogging()

Making sure defaultSuffix doesn’t start with a dot (i.e. “.bar”)

QGCFileDialog::getSaveFileName()

Assert if defaultSuffix contains a dot (i.e. “.bar”)

UnitTest::_getSaveFileName()

Added appropriate AcceptMode to AcceptSave so the OpenFileSave shows the proper Save button instead of the default Open button.

Revert premature assumption that adding support for selected filters in Open Save would not affect all other file dialog operations. As is, unit tests requires all or nothing.

WIP issue #1173. Adding default suffix (extension). While at it, added selected filter support and removed unit test assert about its use.