Update Mission Item icons
Update styling of Editor list
update spacing for text in header
Updated panel layouts for modes
Increased hit area of drawer tab
Merge pull request #544 from arthurbenemann/UI_updates

Ui updates
Changing to android API 18
Prevent Guided mode when not connected
Guided mode listeners for Alt change
Guided mode: allow for altitude changes from side panel
Improved Flight Timer - now independent of the InfoMenubar.

When switching activities, the infer bar is re-instantiated and the timer was being reset. Now Drone State contains the timer.
Merge pull request #546 from DroidPlanner/GuidedMode

Guided mode
Merge pull request #547 from DroidPlanner/flightTimer

Improved Flight Timer - now independent of the InfoMenubar.