Home must be updated instead of replaced.
If not the markerManager can start to put multiple homes in the map.
Adds an option to the markerManager to select if the marker is draggable.

This is needed because markers on the planning screen for instance should be draggable, and the ones in flight data don't.
Merge pull request #195 from arthurbenemann/draggableMarkers

Draggable markers
This fix some problems with the markers