Add diff command.

[BigBlueHat]

Expands two JSON-LD files and compares the expanded results.

This can be extremely useful when moving to a new context file that uses (some or all of) the same term definitions as the previous context file.

This introduces a dependency on deep-comparer which is ISC licensed.

[vorburger]

@BigBlueHat @davidlehn @msporny any chance you would consider merging this? I would use it on enola-dev/enola#779! 😺

[davidlehn]

I had forgotten about this. Is it a good idea to add such things in the tool itself? It's a fairly specific diff. You can get the same effect with a "simple" command:

npx json-diff <(jsonld-cli expand file1) <(jsonld-cli expand file2)

Which seems more flexible since you can control the diff program, diff options, json-ld algorithms and options, filtering through jq, sorting n-quads, etc. Seems like a classic tradeoff of kitchen sink tools vs unix philosophy.

[vorburger]

@davidlehn whether or not you accept this PR is your call! 😄

But if you do not, perhaps its clearest if you simply close this PR, as "thanks, but no thanks"?