cpl-library: CPL library with a new streamlined Interface

The new release includes a substantially simplified interface to include minimal input variables, with function names as close to MPI as possible. The grid setup is handled internally by CPL library using a minimum set of parameters. As a result, coupled simulation can be as simple as three functional calls.

The version number of 2.0.0 represents a new interface which will break previous code using CPL library.

The CPL release contains a full set of examples, documentation and comprehensive website. Note the final minimal coupled example has a minor issue in the coupling constraint on the MD system which will is planned to be fixed in v2.0.1. The example in terms of CPL library data exchange is complete however.