Desktop: Catch possible NPE
Core: added structure to hold the footprint locations in the Drone object

Conflicts:
	Core/src/org/droidplanner/core/drone/DroneImpl.java
	Core/src/org/droidplanner/core/drone/DroneInterfaces.java
	Core/src/org/droidplanner/core/model/Drone.java
Desktop: Plot the camera Footprints on the map
Merge pull request #1210 from arthurbenemann/camera_feedback

Camera feedback