#17 Enum for method/prop names for expectations

[Kareem Fawell]

Instead of using a string to specify a method or property name in an expecation call, provide an enum with an enumerator list of the names of the methods and properties. That would be safer in that a misspelling won't happen (thought a mis-selection could). It would be more convenient in that Intellisense would list the available methods and properties and allow for auto completion.

I suppose for overloads, the enum constants could include the arguments in some kind of name mangling, but that seems like overkill.