Update to Star register enums
Instead of using strings to access register and register fields use enums as much as possible.
Also (related):
- Move use of "enum.h" to a separate class (Abc/HccNames).
- Use input channel to address ABC in register access methods (instead of 1-based index)
Apart from being more logical, this makes a large difference to speed of emulator (it checks the HPR registers on every cycle).