Add shared paths algorithm

[lehtojaa]

Description

Adds algorithm for road network that consists of shared paths. It removes shared path links that go too close to bigger roads.

Type of change

• Bug fix

• New feature

• Other

• Non-breaking change

• Breaking change

Developer checklist

• A CHANGELOG entry has been included (only when change is visible to users)

[lehtojaa]

@JuhoErvasti After opening this PR, it occurred to me the resemblance of the task with the generalize cliffs algorithm. Maybe this could be refactored to functions etc. in that PR? Or having read the discussion under PR #49, what would be the best way forward.

[JuhoErvasti]

@lehtojaa

Maybe this could be refactored to functions etc. in that PR?

I didn't entirely understand how do you mean this, do you mean that the "helper" functions remove_close_line_segments and get_paths_along_roads would be refactored to one function, or the algorithm classes themselves?

As far as I can tell there is a difference between the algorithms in that GeneralizeCliffs straight up removes parts of the "lesser priority" lines which overlap with the buffered "higher priority" lines and can lead to features splitting to multigeometries, whereas GeneralizeSharedPaths remove only entire features which are fully within the buffered "higher priority" lines. Also GeneralizeCliffs removes short lines.

If these are the intended behaviors of each algorithm I don't think they can be entirely refactored, or the behaviors would have to be controlled by parameters. IMO if we're talking about the helper functions I'd prefer to keep the functions separate and not parametrize the behavior as the results are quite different, but that's just my preference. IMO combining the algorithms would make more sense, but I'm not sure which is better from the perspective of integrating the algorithms to a wider system.