Prevent shutdown ordering crashes

* enable TCPLinkTest
* enable FileManagerTest

This mechanism automatically queues data into the correct thread where necessary, otherwise the method is invoked directly with low overhead.

At the same time remove the UDP socket event workaround. It is not a problem.

Also turn on MavlinkLogTest

Allows for UI unit tests to be written:
- Ability to respond to expected message boxes
- Ability to fail test if unexpected message boxes occurs

Centralize all connecting and disconnecting of links through
LinkManager::[Connect|Disconnect]Link api. Connect/Disconnect no longer
allowed through LinkInterface. This allows creation of new
LinkManager::setConnections[Suspended|Allowed] methods to disallow
connections as needed.

When unit tests are being run in TeamCity the host box can end up being
very bogged down with other builds. So need to up wait time, to take
into account CPUs grinding.