linux speech synthesis: switch to eSpeak

Fixed Google Earth file location for Mac users

Only a single MAVLink dialect is supported

HIL cleanup, ensure correct init in X-Plane

Added 2 kPA offset to pressure measurements to get HIL closer to reality

Message view

Warnings as Errors off by  default

Also changed WarningsAsErrorsOff to WarningsAsErrorsOn to be used by
TeamCity builds.

Removed completely unused variables. Ifdef’ed out variable which is
referenced from commented out code.

Removed -Werror for Mac since QT wont build otherwise.

mapripper: autocontinue to next zoom level after 3s

Don't use native menu bar on Linux

Fixes Issue #542

More failed QObject::connect calls

QSerialPort emitting stream of errors

Readme Update

Fix distance to next waypoint widget in QuickView.

This patch fixes a bug that display 0 for distances to waypoint more
than 10km.

Besides that, it also homogenize the naming of the label to
"distToWaypoint" instead of "distToWP". Old configuration files (in
home directory), should be hacked or removed in order to see this
change.
Signed-off-by: Paul Chavent <paul.chavent@onera.fr>

Flightgear HIL: remove disable-intro-music argument 

Also commented out noisy serial link error output