Allow choice on Line Intersection - Allow "tighter" yet non-intersecting lines?

[erwin]

I'm not sure if this is related to #115

Sometimes I would like a line like this one to be closer to the adjacent line, without requiring a whole blank line in between:

I think it always makes sense to intersect with lines you've actually touched, but shouldn't it be optional to intersect with adjacent lines?

Somewhat related, there's a cool "traintrack" effect when you lay lines very close together, for example, whenever you add a line in here...

It's auto converted to:

Shouldn't it also be possible to just have a line not converted to the traintrack pattern though?