Templates with the pre-defined code hull for the reader_wrapper,
writer_wrapper, and key_holder were created.
A "cookbook" of how to expand this TEMPLATES to create type specific IDL
conversions was also added.
The "code generation" is kept general to allow a code generator to
automatically produce this wrappers in the future.
The instantiation of the KEY related entities is moved outside the DDS
Endpoints (Currently only changed in DDS Writer). Define new KEY_HOLDER
entity that is responsible for all Key related type-specific code.
Fix syntax of DDS Writer, and misc code refactoring.
Initial imeplementation of the RTPS Reader side of the history cache.
A key_hash_generator entity that will house the future MD5 hash
calculation was also added, along with the entity definition of
key_generator, which has to be implemented per-topic-type.
