QGCMapPolygon select vertexes functionality

Help with Qt 5.15 and 5.14 integration

Remove QT_VERSION for old and not supported Qt versions 

Fix location of Qt.inputMethod.hide()

Remove missing support for QGCView fact missing overlays

Cut over to new JSON translation system

Fix locale setting

Cut over to new JSON translation system

New Crowdin translations

Fix location of Qt.inputMethod.hide()

Remove missing support for QGCView fact missing overlays

Add invalid vertex index warning