add compile-time type system for MPI data/ops

The front-end traits:

- UPstream_dataType trait:
  This wrapper is unwinds the type to check against base/alias, but also
  checks if it is a component aggregate of a supported UPstream data type.
  This will be that main entry point for usage.

- UPstream_opType trait:
  Provides a mapping of OpenFOAM ops to their MPI equivalent.
  The \c opcode_id is the corresponding internal representation.

The lower-level traits (not normally used within coding)

- UPstream_base_dataType trait:
  Tests true/false if the specified data type has an internal MPI equivalent.
  The \c datatype_id is the corresponding internal enumeration.
  Even if this tests as false, it will always return \c type_byte as the
  fallback for general contiguous data

- UPstream_alias_dataType trait:
  Provides mapping for <int/long/long long,...> to the fundamental 32/64
  integrals, since <int/long/long long,...> may not otherwise directly map
  on all systems.

NOTE: can use the updates Test-machine-sizes test application to
determine if all data types and aliases are properly defined on
different systems

- this will allow send/recv/broadcast of various data types directly
  without reinterpreting as bytes. No performance benefit, but makes
  programming more flexible. In addition to the normal MPI types, also
  provide some convenient groupings such as double[3], double[9] etc.

- the additional user-defined data types are created on the start of
  MPI and removed before shutdown

- provides an additional means of process synchronization