Improved Command Rendering

[PeteMichaud]

I don't know if you're interested in improving the code after all this time, but just in case:

mmps has an issue with rendering things like the grid and analemma because of some segmenting logic in PlotLineAux. I fixed this logic in my project and the changes wouldn't be that hard to backport. Check out:

https://github.com/PeteMichaud/MapProjectorStudio/blob/master/MapProjectorLib/Image.cs

The relevant portion is PlotLineSegment which is the equivalent of PlotLineAux in mmps. I'm doing the bounds checking a little differently so that only very tiny segments at the margins are potentially dropped, which makes the whole thing behave more smoothly.