Shallow comparer

[xaviergonz]

• Added unit tests
• Updated changelog
• Updated /docs. For new functionality, at least API.md should be updated
• Added typescript typings
• Verified that there is no significant performance drop (npm run perf)

Fixes #1561

Adds comparer.shallow for shallow comparisons of objects/arrays

Will do a backport when/if accepted

[coveralls]

Coverage increased (+0.007%) to 93.388% when pulling 9005817 on shallow-comparer into 0502539 on master.

[danielkcz]

Please, don't reformat changelog :)

Otherwise, I suppose it looks good given you made a new test and existing ones are passing. But I would rather let others to decide as I don't use these advanced features.

[xaviergonz]

The reformatting was actually done by husky on commit hook :-/
I have to actually use --no-verify on commit to skip husky so it won't get reformatted, but I'll do it

[danielkcz]

Sorry, I guess that's my fault, I've changed lint-staged config to include md (for docs), but the actual prettier script is formatting docs folder only. I suppose it's not entirely wrong to have the changelog formatted as well, I will take care of in a separate PR.

[xaviergonz]

No worries, I guess it wouldn't hurt to have a PR that basically runs prettier over everything :)