Start of work on Redundant Link. This first step modifies the exisitng link agent to allow it to be given an id (through the -link_id flag) and to send ivy messages of a different format (when -redlink is set). The messages are sent within the TELEMETRY_MESSAGE message as a  ;sv (colon-seperated-value) which are listed to by the link_combiner.py agent.
Started the second step of the redundant communication link, writing the Link Combiner agent. This agent receives ivy messages from the link agent(s) when they have a name specified, removes duplicate messages, then sends ivy messages of the same format that the link agent used to send messages.
Added GUI in GCS for multiple links. The information for this is sent from link_combiner.py in the LINK_STATUS message. The GCS now has a page in the notebook named Link, the ratio of active links appears in the main link indicator, and messages when a link is lost or gained are displayed in the console.
Adding support for displaying link status information when multiple aircraft are connected through the same link. Also added support for recording link status information in flight logs and displaying it during a replay.
Added sample redundant communications session to control_panel.xml.
Merge pull request #429 from uaarg/redundant_comms

Redundant comms