Module port description/declaration

[dcwhite]

Ideas for making this more declarative:

• use a macro that takes name, index, and type, and generates all appropriate methods.

Should feed into ModuleFactory in a clean way (may need to refactor the module construction logic).

[dcwhite]

Macros are now used in Module class declarations to describe ports as outlined above (as of 90a8e43). ModuleFactory still needs some work though, I will make a new issue for that and file it under milestone C.