Unable to register custom Comparators

[kevinarcher]

This commit introduced in PHPUnit 4.1.0 seems to have removed the ability to register custom comparators.

f0322b6#diff-bc1620baa64f3fb88768712abdc0e2fbR152

Is it possible to add support for this feature back, or is there a better way to validate objects equality in a custom way?

It's something that I've often relied on to prevent flaky tests when working with objects containing DateTimes using mocks with and assertEquals.

I haven't tested it recently, but in my experience the $delta parameter was not applied when comparing 2 objects directly containing a DataTime in a field.