Merge pull request #2846 from dogmaphobic/mapCache

qgcresources.qrc

qgroundcontrol.pro

qgroundcontrol.qrc

resources/notile.png

src/FlightMap/FlightMapSettings.cc

src/QGCToolbox.cc

src/QGCToolbox.h

src/QmlControls/OfflineMapButton.qml

src/QmlControls/QGroundControl.Controls.qmldir

src/QmlControls/QGroundControlQmlGlobal.cc

src/QmlControls/QGroundControlQmlGlobal.h

src/QtLocationPlugin/OpenPilotMaps.cc

src/QtLocationPlugin/QGCLocationPlugin.pri

src/QtLocationPlugin/QGCMapEngine.cpp

src/QtLocationPlugin/QGCMapEngine.h

src/QtLocationPlugin/QGCMapEngineData.h

src/QtLocationPlugin/QGCMapTileSet.cpp

src/QtLocationPlugin/QGCMapTileSet.h

src/QtLocationPlugin/QGCMapUrlEngine.cpp

src/QtLocationPlugin/QGCMapUrlEngine.h