Add support for an equals(...) method

[tghamm]

It would be nice if there were an $equals(..) method that could be created optionally per type and defined in the parser settings, similar to the $merge(...) method.

Ideally you compare the value of each property as defined by the passed in PropertyBag collection and parser options. It should test failure and return quickly where possible. It should handle deep collection comparison as well as custom class comparison using the `euqls(...) method internally.

[tqheel]

This is a test comment. Hopefully it will show up in Slack channel. Booya.