Removing all SLUGS autopilot-specific code.
SLUGS has maintained their patches out-of-tree for a long while now.
These will eventually get merged back in, but it'll be easier to evaluate them as fresh commits instead of modifications to this old & dead code, so we'll delete this for now.
Removing old file containing dev notes.
Merge branch 'master' of https://github.com/mavlink/qgroundcontrol into del_slugs
Ignore .qmake.stash

Qt5 qmake seems to leave this handing around
FileManager UnitTest back on
Better output for signal failures
Set correct component ID

Need to disambiguate from video stream messages
Silence release build compiler warning
Bump signal wait time

When unit tests are being run in TeamCity the host box can end up being
very bogged down with other builds. So need to up wait time, to take
into account CPUs grinding.
Merge pull request #786 from DonLakeFlyer/FileManagerUT

File manager Unit Test back on
Merge pull request #768 from Susurrus/del_slugs

Delete outdated and unused (all) SLUGS-autopilot-specific code
Merge branch 'master' of https://github.com/mavlink/qgroundcontrol into valgrind_fixes