Further consolidation of Plot code into ChartPlot. Also removed some unused variables from LinechartWidget.cc. Also only active curves are recolored in the IncrementalPlot class.

Moved all shared code for IncrementalPlot and LinechartPlot into a common ChartPlot superclass. Also recoloring the background of both widgets now works when switching between color schemes.

Substantially bugfixed and improved deactivation/activation and persistence of widgets. A lot of testing of Google Earth view, only minor improvements

Working on QGraphicsView-based local waypoints interface supporting drag-and-drop, commented code, fixed Google Maps interface, added mouse and SpinBox zoom to HSIWidget, fixed MAV-based coloring and stylesheets - MEGA COMMIT

Improved runtime performance, currently hunting down a bug where the whole application gets repainted although only parts of it are refreshed