Trial manouevre

[rooiedirk]

Inspirated by the functionality of some modern radars, I added this also to "O".
With a trial manouevre you are able to see what the result will be from a planned course or speed change. Special on sailing boats you can check the result of a tack before acting one.
At the moment it looks like this.
Picture one. Situation when I plan a tack.
Picture two. Doing the trial manouevre. Note the red(danger) bar at the bottom. There you can enter a new course and speed. On the chart area you can see the own ship turn to the new course and the prediction line is also set for the new speed. For all AIS targets you can now see the will be CPA etc.
Picture tree. If you are not happy with the result it is possible to see wat will happen if you wait a bit. By moving the slider the own ship, as well as all the AIS targets are moved into the future. Just choose your moment to tack.

At this moment the only way to enter the Trial mode is by the menu.(under tools). TODO is add it to the right click menu, when clicking on own ship. Also todo changing course and speed by dragging the predictor point.

Pls give it a try so I know it works before making a push request.
Remarks and additions are also welcome.
https://github.com/RooieDirk/OpenCPN...trialmanoeuvre

Dirk