* fix issue of 'Error writing to QHostAddress("")'

(cherry picked from commit 9450b97c94af8c4919151ae91e9c7601b74e95ad)

* remove obsolete comments

(cherry picked from commit 7ff3b0049b9f91f39f5e764c92058ba1c0484308)

* add comment on why the additional condition check is required.

(cherry picked from commit 149e19b7c90f178f8a7e8a544243ce7acd642fe8)

* MockLink is always MISSION_ITEM_INT to catch bugs in unit tests

* Fix typo

(cherry picked from commit e049bc1c3c4b63eb7e7a47df4c9d187b36ef8992)

* Add 3DR Solo, Parrot Discovery video sources

* New solo video handshake, remove stale code

* Allow use of AutoConnect and HighLatency options for most link types.

* Remove isAutoConnectAllowed and isHighLatencyAllowed methods and assocated Q_PROPERTYs from LinkConfiguration class.  Allow user to configure these properties on all link types.

* Fixed 5.15 build on Andoid (removed deprecated API)

* Removed -nostdlib++ hack fix

* APK build error fix

(cherry picked from commit 2faa80dacfa726f1ece6720934e5b5f81ca4b754)

(cherry picked from commit 4b73b4a49f542e2e051da6ee50e54f7fe06a13b1)

* Use correct key names

* Rewrite FTPManager

* Fix Reset Session at end of download

* Fixes for metadata download

* Remove unneeded mutex

* Cleanup LinkInterface, fix connect/disconnect bug

* Clang 12: Fix Autopilotplugin compile warning

* Clang 12: Fix Vehicle CompInfo compile errors