ST_CreateTopoGeo drops lineal input boundaries

[strk]

When passing mergeable lineal input to ST_CreateTopoGeo such merge happens thus failing to add node where input lineal boundaries were.

This seems to go in the opposite direction of explicitly creating nodes where Puntal inputs are given.

This ticket is to make sure input nodes are retained instead, no matter degree. Ie:

This input collection (2 lines):

{{ o——o——o }}

Should result in 2 edges and 3 nodes (rather than 2 nodes and 1 edge as currently happens).

[strk]

Fixed by r8062 which probably also slowed down the function by a pretty high factor (working on that next)