Add support for 4502/4510 CPU from Commodore 65

Hello Michael,

I have added support for the 4502/4510 CPU, as found in the Commodore 65 prototypes.

In the process, I have made the addressing mode handling a little more flexible, by replacing all direct references to addressing mode numbers with lookups based on the addressing mode name.

I have added a test for all the new 4502 opcodes, and the test suite passes on my machine at least.

Please let me know if there are any issues with the patch set, and I'll do my best to accommodate.

Paul.