Mission/Survey related fixes

* If new Survey is set to altitude fixed value then use mission default
altitude
* If the user applies a new altitude to the entire mission change
surveys to fixed altitude and apply altitude

This way if the user switches away from manual the altitude is preserved

Stable merge

Message ID buffer overrun

* 'master' of https://github.com/mavlink/qgroundcontrol: (37 commits)
  Update ISSUE_TEMPLATE.md
  Update ISSUE_TEMPLATE.md
  Create ISSUE_TEMPLATE.md
  Revert "Remove FileManager unit test"
  Revert "Temp removal of Onboard File"
  FileManager: fix upload complete
  QGCUASFileView.cc: fix upload complete
  Flight display: Fixed TypeErrors on startup without gstream installed
  Fix timeout logic
  10 sec timeout on vehicle
  Stack callsign below altitude
  Flight display: Create property variable
  Flight display: Remove video record button when gstreamer is not installed
  Add missing lib
  Flight display: Add callsign to transponders
  Add missing lib
  Better display of vehicle indicators for multi-vehicle
  Add support for ADSB vehicle display
  travis-ci fix indentation
  travis-ci fix google play deploy and quiet wget
  ...

Correct hiding of heading on TAKEOFF command

Plan: Update home position when loading plan after vehicle already connected

Re-enable FTP in menu

Fixups for building without gstreamer/videostreaming support

This reverts commit ac73682a.

This reverts commit 6620f803.

Previously, a completed file upload lead to this assert:
    Q_ASSERT(!_ackTimer.isActive());
because _closeUploadSeesion() was called twice, thus activating the timer
twice.

ADS-B vehicle timeout and stacked callsign

Linux: Add missing lib

Flight display: Add callsign to transponders

Linux: Add missing lib

Better display of vehicle indicators for multi-vehicle