example of mutator pattern

following 7.2 of http://cran.r-project.org/doc/contrib/Genolini-S4tutorialV0-5en.pdf

apparently this is how to do mutators "right", it is still a bit goofy, but I don't mind it as much.  Also, it might be a good idea to make a class of the algorithms rather than leave them as a list.  That would prevent any generic list from being set here, though error handling in the initializeProcessInputs could probably handle that case.