Editor: Allow negative altitude mission planning
Merge pull request #1231 from DroidPlanner/negativeAltitudes

Editor: Allow negative altitude mission planning
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into dp_3dr_services

Conflicts:
	Android/src/org/droidplanner/android/proxy/mission/item/fragments/MissionTakeoffFragment.java