We need a way of drawing thicker lines on the back buffer GL surface

[torriem]

In order for youturn and hydraulic lookahead to work properly and reliably with headlands, it would be better if we could draw those lines on the back buffer using the same number of pixels as AOG does. OpenGL does not support line widths other than 1, but since the back buffer is a over-head view, we should be able to calculate the number of meters in a pixel and when drawing the Polygon make it a triangle strip or something.