[middleware] Introduce stuff for HLA as a middleware

Provides an implementation for HLA as a standard Morse middleware.
It does not provide API for the whole HLA standard, but only:
  - time management
  - objects attribute management
  - synchronisation point

Other possible interesting points to manage in the future is:
  - interactions mechanisms
  - region management

Provides also two examples, working with the CERTI Example fed Test.fed
[blender/main] Be more robust in case of exception in Datastream Manager creation
[builder] Add an entry for hla stream manager
[multinode] Rework hla multinode to use stuff defined in hla_datastream
[mw/hla] For now, provide a certi message_buffer with Morse

It may be removed when one will be officially distributed with CERTI
pyhla.

Update modules to use this inner implementation.
[doc] Mention MOOS improvement and new HLA stuff