Fix horizontal spread when multiple actions continue from a single tipping point

[kordejong]

Example:

current current 2030
current a 2050
a b 2060
a c 2060

Vertical lines still overlap because the action end of action a it not adjusted for the transformation to b and c. The action begins of b and c are adjusted.

[kordejong]

In a pathway map graph, each action currently ends in a single ActionEnd node, which may be linked to multiple ActionEnd nodes. The one ActionEnd node has a single x-coordinate, which is used for all transformations to other actions. To solve this issue, pathways must be encoded in the pathway map graph as separate paths, so that the position of each ActionEnd can be tweaked. This is possible, but touches various parts of the package. More than a little amount of work. Lowering priority until everybody agrees this is necessary.