Calculate Type Use of Methods:
  This procedure fills in the missing information in the TypeUse
  objects. (1) The 'needHeader' attribute is calculated. (2) The
  reference to the named DefinedType is filled in.

  The rules for ArgumentDecl and ReturnDecl are nearly the same.
  The only difference is in the treatement of the PrimaryType.
  If a method, Foo::bar(), returns a class 'Bar', the header file for
  Foo only has to forward declare 'Bar' as a class. It does not have
  to include the header for 'Bar'. Thus 'needHeader' is always false
  for ReturnDecl.

    Primary Type
      For ArgumentDecl:
        'needHeader' is the negation of the TypeDecl's 'isRef' attribute
      For ReturnDecl:
        'needHeader' is always 'false'

    Template Argument Types
      These types only exist when the declaration is for a templated
      class. The 'needHeader' flag for thes types follows the value
      determined for the primary type.

    Array Dimensions

      These aren't really types. They are symbolic names whose
      defining header file must be #included. This goal is
      accomplished by declaring the name as a NonClassType. 
      'needHeader' is always 'true' for these types.

    Initializer Type
      This is really a symbolic constant, like Array Dimensions.
      It is treated in the same fashion.      

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Update Type Registry with entries for Entities.

    For each Entity
        For each CodeCatetory
           Expand the CodeCategory's EntityName and HeaderFile pattern
           for the current entity. Use this information to create a
           SimpleClass type and register it.