Use C++ classes as base

[langmm]

Create C++ classes replicating major methods except serialization (#72) with Python wrappers (Python API preferred or Cython)

Communicator (Comm) Classes (in order of priority)

• Base
• ZMQ using zeromq C++ library directly (previously used czmq which has added complexity to installation)
• Async class (can use any base class, but messages are queued and sent/received asynchronously using threads)
• IPC class using sysv queues (lower priority)
• RMQ class (lowest priority)

Methods

• Constructors/destructors that check for address information in environment variables and manage underlying resources for the base class communication (e.g. queues)
• Send/Receive small string messages
• Send/Receive large string messages by breaking up the message and sending the pieces to a temporary comm identified by header information sent to the recipient
• Open comm, opening connections and altering state that can be checked via method
• Close comm, closing connections and altering state that can be checked via method
• Methods for checking if messages are available for receipt or if messages have not been received
• (AFTER Move serialization into C #72 COMPLET) Send/Receive non-string messages

Additional requirements

• Tests for C++ classes
• CI for C++ tests
• Python wrapper classes serve as drop in replacements for the existing Python comm classes and pass interface & connection driver tests (parts of existing comm tests may be modified where they touch non-stable API).
• C wrapper
• Fortran wrapper using ISO_C_BINDING
• (MAYBE) R/Matlab wrapper directly wrapping C++ instead of Python?