Interprocedural DynamicTypeResolver

• Closes #45 (closed) (see there for the idea for the implementation).
• Alters VariableAction to take Expression as argument (either NameExpr or FieldAccessExpr).
  • Affects Interprocedural{Action,Definition,Usage}Finder, VariableAction, VariableVisitor, GraphNode.
• Expands the CallGraph API (obtain calls from/to a given method, obtain methods called or that will call a given method).
• Fixes bug where movable definitions were created incorrectly (VariableAction#245)
• Now accepting FieldAccessExpr completely. CAVEAT: we accept as is, but we should only do so when it is of the form a.b.c.d, not a().b().c().d. Currently, we search for a matching VariableAction, but that may not always work.