Ability to merge trips

Title gives rough overview, but my idea is basically a “trip” instead of current implementation (where you drive from A>B and thats a trip, then another trip is B>A) would be say A>B>C>A, with B & C as “stops” during the trip
This has very little purpose as of right now, but could be very useful for powering statistics later on, so that way you could have a unified trip of say “grocery store” or have a roadtrip where you stopped 3 times be counted as one long trip rather than 4 separate trips

The issue names no files, tests, or entry points. Start by clarifying how trips and stops should be represented, including how existing A>B and B>A records are merged and how statistics should use the result. Done should be defined by agreed behavior and tests for these cases.

Written by the indexing model from the issue text.