Video replay tool

A tool to replay a video of a flight in sync with the replay of the log. The documentation is available here : 

https://wiki.paparazziuav.org/wiki/Video_replay

To test it, you need to delete your conf/control_panel.xml, in order for the make to regenerate it with the new tool. A make clean doesn't do it.

Would make sense to call this ivy node Video Synchronizer instead of Example1 here...