Re-examine the segment path-finding algorithms

[pklampros]

The segment path-finding algorithms have various quirks outlined in PR #352 which made the overall code modular and provided a sample module which is essentially a stripped-down one-to-one version of the bigger all-to-all algorithms used for segment analysis. Through the PR discussion various points were raised regarding the algorithms themselves which require further understanding and review (implementation details regarding the new modularity were agreed-upon). The PR was merged, so this issue is meant to act as a link back to the PR to allow the discussion to continue.