Fix droidplanner issue #675: updated the flight mode spinner bar so that its view is updated only after confirmation of the mode change by the drone.
Code cleanup.
Merge pull request #687 from tensafefrogs/master

Update README.md
Merge pull request #686 from ne0fhyk/fix_issue_675

Fix incorrect Mode Button behavior #675
UI: Change the way the UI responds to a wrongly made polygon.
Editor: Don't raise an exception when trying to modify an invalid survey mission.
Merge pull request #688 from arthurbenemann/survey_ui_fix

Survey UI fix
Version: Releasing version 2.2.4