[gps] Add a new GPS based on the datalink
[fms_network] Added multicast support
[ground_segment] Added NatNet to ivy service
[ardrone] Updated gains and reference model for inside
[modules] Added a module for following based on received remote GPS
[follow] Fixed following module
[datalink] Fixed some small issues with UDP datalink
Merge pull request #648

Full optitrack implementation.
Only AHRS GPS frequency scaling needs to be implemented to fix the issues with using the optitrack for heading.

Added gps based on information gathered through the datalink
Added ground module to transmit optitrack packets to the drone