Harden FTPManager::download against packet loss

Updated mavlink forwarding implementation to forward all mavlink messages received on all channels onto a single UDP port. A new mavlink forwarding UDP link is created if forwarding is enabled. The mavlink settings page now has a Fact checkbox for enabling forwarding and a fact text field for specifying the host name.

Added mavlink forwarding as an option to UDP connections. Enabling this setting will cause every mavlink packet received by QGC to be forwarded on the link, with the exception of packets originating from said link.

New qml base log replay status bar

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

Prevent shutdown ordering crashes

Plus other auto connect bug fixes

Was failing on slower ArduPilot boots. Also could fail on PX4 boots
which required px4io flash on boot.

- Also fix vehicle selector dropdown in toolbar

Refactored PX4 radio config to work with both PX4 and APM