Fixes Issue #1162

- 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.

- 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

QQuickWidget can’t handle this

Now works for more than Serial links