GCS Share: copy welcome qml files to share directory

This is largely redundant but facilitates using the Qt
deployment tools.
OSX Package: distribute QtQuick files

macdeployqt now works properly. it does requires qml files
for it to parse to exist in the package, so for files that
are in a resource (e.g. welcome) they must be duplicated
to the share directory.
Windows Package: distribute QtQuick files

windeployqt now works properly. it does requires qml files
for it to parse to exist in the package, so for files that
are in a resource (e.g. welcome) they must be duplicated
to the share directory.
OSX: install OSG / SDL

Restore these. No reason not to package if they
are present.
OSX App: switch how we include Info.plist
GCS: forgot to check in Info.plist
PFDQML: switch to QtQuick
Welcome: update to Qt Quick
GCS: fix some compilation warnings
QML View: switch to Qt Quick
PFD: remove broken elements

The roll and pitch indicators were not working
because StabilizationDesiredType is undefined.
Removing these entirely.
GCS Added useSessionManaging option to globalsettings
GCS Added generalSettingsChanged signal to globalsettings
GCS Added useSessionManaging option to globalsettings ui
GCS/TelemetryManager set all objects as present when the gcs starts
GCS/TelemetryMonitor allow for user selectable non managed sessions
GCS: keep browser buttons working regardless of session state

This is a workaround for the fact the modem doens't trigger
a correctly opened state. It also doesn't even start handshaking
by itself, so the session management never even fails.

In general it's useful to keep the browser buttons working for
debugging purposes even if a valid session hasn't been established.
TabletControl: use the path follower FMS for PH and RTH

This code was written before the more sophisticated path following
code and explicitly tried to set the position and use the path
planning code. Now it behaves like the transmitter and simply sets
the flight mode to PositionHold.
SparkyBGC: needs LoiterCommand included
VtolPathFollower: makes RTH altitude and RTH velocity adjustable in settings