Use Hex diff library for diff and patch

[dgoldie]

[andyl]

Doug, thanks for this!

Please submit a diff solution that will convert to/from JSON. The expression Diff.diff("asdf", "assdf") |> Jason.encode!() raises an error.

Also: if you can come up with a solution that does not require use of 3rd party dependency, that would be optimal. But in the near term, I would for sure prefer a dependency vs shelling out to the linux utils.

FYI I added a bit more context to Issue #2.

Thanks again for this PR!

[andyl]

Just saw this on Elixir Forum - maybe a solution?

https://elixirforum.com/t/serialize-and-unserialize-structs-tuples-keyword-lists-atoms/40794