[WIP] Multiple: Connect end points with degree 1

To-do: Tweak algorithm
To-do: Repeat step until all nodes with degree one are connected (if possible)
To-do: Discard unsuitable segment if it impedes the addition of a good segment.
[WIP] Multiple: Remove obsolete method
[WIP] Multiple: Remove redundant method
[WIP] Multiple: Add TODO about weighted history
MultipleCurves: Improve modifier

Adding a fixed constant is a bad choice because it does not account
for the distance between nodes.
This commit introduces better modifier that builds upon the weight
derived from the distance between the nodes.
MultipleCurves: Run on all new nodes with degree 1

Implemented as recursion, but it can easily be refactored to a loop.