Refactoring WP interface, somewhat brittle and untested at this point - use the master branch if you need stable code right now

Changed waypoint list file format (old files are not compatible anymore!), added file version check, now all waypoint entries should have an entry in the waypoint list file - although qgc does not use/read the orbit_direction and param1 fields. QGC writes the value of orbit into param1 and 0 to orbit_direction (this should and will be changed later!)

fixed some waypoint initialization problems (action and frame were not updated correctly in the waypoint list when read from the waypointplanner

corrected a compile warning in Wayppoint.cc, made adaptions to Freenect for the current revision of the code (update libfreenect repository!), commented out pixhawk poi mavlink code - needs fixing

Major refactoring of the waypoint code. The new design fits the model-view-controller pattern better.