* add `merge_by_distance` node
* remove unneeded features of petgraph
Also re-arrange module slightly since because functions are no longer
async, there was name shadowning with the old arrangement.
* remove region if start or end segment is removed
* remove stuff I ended up not using
* "algos" -> "algorithms"
* Code review pass
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Co-authored-by: Keavon Chambers <keavon@keavon.com>
0570edc463