Request: Enhance boat course vector

[hkapanen]

Current boat course vector can be hard to see on top of a busy chart. I'd suggest making its width and colour configurable to help the situation.

[wellenvogel]

The width and color can be changed in the settings/navigation with circle width/color. This currently both changes the vector width/color and the circle width/color.

[hkapanen]

Ah, did not realised that they are governed by the same setting as I personally don't use the circles at all. Created PR #360 to make this clearer.