feat: support for arrays of mergeable objects in the “with” argument of “$merge”

[azaslavsky]

This is a working implementation of the feature proposed in #14. It would also close #12.

[coveralls]

Coverage remained the same at 100.0% when pulling e84920a on azaslavsky:arrays-for-with into d847ec3 on epoberezkin:master.

[epoberezkin]

@azaslavsky Thank you, I will review

[vganapat]

Hello, I was looking for the fix to #12 and was wondering, is there an update on the PR review?

[epoberezkin]

The fix to #12 is very simple, there is a separate PR for that. To support an array instead of a simple schema, there is no need to change the package completely. Instead of passing "json-merge-patch" package as is, you just need to pass a wrapper around this package that understands arrays.