Move ArduPilot preflight check handling to generic QGC

http://www.wolframalpha.com/input/?i=!s+%7C%7C+(s+%26%26+a)Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Also hand carried text to speech changes from Stable to master. Plus
unit tests for that.

If there are dropped packets during a burst download, the offsets and sizes
of the missing chunks are stored in a queue, and after the burst is
completed, they're requested individually.

This stores the last request and resends it after a timeout, with a max
of 6 retries.
It also checks for old incoming packets and drops them.

Some crazy shit in UAS.cc was using an array of 256 bytes to handle received messages and mapping them to components. Well, any message ID over 255 would cause a buffer overrun.

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

* Some code moved to Vehicle

Moving source files into Vehicles as it is a more coherent place.

Forcing QGC to use Mavlink V2 if vehicle supports it.

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

This reverts commit ae976049ca7b4818616e6b8be07a028fc7dfc26f.