More cleanup and improvement

[gphat]

• Properly privatize objects associatedClass var
• MoeClass:
  • Ditch overloaded constructors for the implicit one with Option and defaults, then use named params
  • Scaladoc
  • Refactor attribute & method methods to be more idiomatic
• Clean up MoeAttribute
• Show how to document a case class in AST
• Remove the last of the HashMap that were peppered around and unnecessarily mutable
• 2-space indent a bunch of tests that missed the four-space-pocalypse