LinkInterface and Vehicle uses mutexes to synchronize writing bytes to the link instead of queued signals

App messages now use simple modal message dialogs. Vehicle messages continue to use non-modal popup.

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Visual accel cal

Move ArduPilot preflight check handling to generic QGC

Fix merge issues

This reverts commit 9f41c6ea.

Must memset structures before use.

This makes VehicleComponents reusable from core plugin without
requiring override of prerequisiteSetup

_finalize methods need information which is not available if all you
have is a mavlink_message_t

- Sensors summary now shows you how man compasses you have
- Fix for APM accel cal. Can only use first accel offsets.

Strings can be expensive to create, all the issues with allocation,
copy of the char members, conversion to UTF-16. QStringLiteral creates
one in compile time.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Also fixed problem with setup complete signaling after positive
calibration completed

There are many ways of iterating over lists in C++/Qt.
In the specific case of QStrings, it is known [1] that using
foreach with const references avoids the creation of new
QString objects in each iteration, reducing the time consumed
by the loops.

[1] https://blog.qt.io/blog/2009/01/23/iterating-efficiently/Signed-off-by: Anselmo L. S. Melo <anselmo.melo@intel.com>