Updated test messages and added dynamic user-defined function resolution

Hi.

I corrected a couple of test messages as to what the output of the tests really is.

I also added 'dynamic' user-defined resolution. That is, if the user-defined function cannot be found in the hash that is supplied for a function lookup, a slot called 'RESOLVER' that is supposed to contain a resolution function is looked up and, if it is found, it is invoked (with name of the user-defined function) and it is supplied to return a Function object representing the user-defined function. There are a number of different ways to achieve the same effect here, but this was one idea.

Cheers,

- Bill