Remove Arrows from Mapmaker

[napakalas]

As discussed, the arrows on Mapmaker are difficult to see and do not add significant value to the maps. The attached picture compares the current Mapmaker with arrows (first image) and without arrows (second image). To improve visual clarity and consistency, we should remove the arrows.

Current rendering with arrows

Updated rendering without arrows

[dbrnz]

I think the best way to do this is to have draw_arrow() do nothing by default and to have a new option, say --path-arrows, to actually add arrows.

[dbrnz]

Resolved with PR #117.