DSS2 — Simplify representation of Handle Types

The use of abstract valuetypes for handle types in the current
DistributedSimulation IDL requires a user to have matching
implementations of the handle and the handle factory for both the client
federate and RTI. Because it is usually an RTI developer who provides
the implementation of these handle types and their corresponding
factories, it is unnecessary to use a valuetype to create this
definition. It is recommended that valuetype definitions of handles be
replaced with IDL interfaces. That is, in the section labeled “Handles”
from pp 1-9 to 1-10, the word “valuetype” should everywhere be replaced
by “interface”. Paragraphs 5 and 6 on p. 1-9 are replaced by the
following:

Each kind of handle is represented in IDL as an IDL interface, e.g.,
ObjectClassHandle or FederateHandle. An RTI implementer will create an
implementation for each such interface., the details of which are hidden
from the federate developer.
In paragraph 7 on p. 1-9, the words “concrete valuetype” should be
replaced by “interface”.
In the IDL, the HANDLETYPE macro is replaced by the following:
#define HANDLETYPE(A) \
interface A

; \
interface A##Factory

;

Replace valuetype definitions of handles with IDL interfaces.