Time to layline

[petsicola]

I close this issue i explain it in #184

[panaaj]

Using this issue to address "Time to lay line it would be useful because we can say to the crew when we are going to take the next tack or jibe."

[panaaj]

The specification details the path navigation.racing.layline to hold both time and distance to the layline.

These values will not be populated by Freeboard-SK but can be displayed if available.

The calculations could be added to an existing plugin or one created for populating racing data.