plugin architecture for additional assertions

[jamestalmage]

allow users to create reusable assertions by calls to some global method

addAssertion("assertIsAwesome", function(args): ... : end function )

This would populate some global associative array with methods that would get copied to each new t parameter passed to test. It should fail if users are accidentally overriding an existing method (maybe an optional force parameter to allow overriding?). It would also require some documentation on how to correctly fail an assertion so behavior remains consistent with other methods.