Guided: Just allow entering guided mode via the mode spinner or RC controller
Guided: Cleaning up old code, using the Altitude Object.
Guided: Add a safety check tp methods that change guided via the UI

Refactoring some names to match the new function.
RC Setup screen UI updates
Default Alt
Heartbeat: clean up

1. remove the Calibration.isCalibrating() check from heartbeat class
2. add the Calibration.isCalibrating() into TTS class
Calibration: check if really doing calibration

if ‘msg’ is empty then the event is triggered outside of ‘calibration
mode’ - we need to reset the flag and re-trigger the HEARTBEAT_TIMEOUT
event so TTS can announce the Data Link Loss event
Drone: Bug Fix

The DroneEvent needs to be initialised first since other DroneVariables
are going to use drone.events to add their callbacks
Merge pull request #571 from azrin1972/BugFix--Exception-upon-startup

BugFix: move event to the top of the list of creation
Merge branch 'master' into Calibration-Update
Merge branch 'master' of https://github.com/jason4short/droidplanner into UI_Jason2
UI update - increase the size of the drawer in flight screen
UI Update - Made alt "0.0" by default
UI - cleanup drawables folders, set the home to correct new icon
Merge pull request #573 from azrin1972/Calibration-Update

Calibration update
Merge pull request #570 from jason4short/UI_Jason2

RC Layouts
Merge branch 'master' into GuidedChanges

Conflicts:
	DroidPlanner/src/org/droidplanner/drone/variables/GuidedPoint.java
Merge pull request #549 from arthurbenemann/GuidedChanges

Guided Mode changes
Submodules: Updating submodules to API 18

Please refresh your local submodules by running "git submodule update -f"
Merge pull request #576 from arthurbenemann/submodules

Submodules: Updating submodules to API 18