Design and implement model input

[HendrikTolman-NOAA]

The basic calling structure for model input (forcing) has been put in place in PR #19, Issue #30. This issue is intended to build out the forcing input up to and including the actual data flow. The following sub-issues have been identified in out project management plan:

• Address uniform input forcing fields (Issue Uniform input forcing fields #34).
• Implement forcing input read from file (Issue Forcing from file #35).
• Implement forcing input provided by coupling (Issue Coupled forcing #36). Note that the logic for this was not yet implemented full in the above mentioned PR and issue.

Apart from forcing input, a numerical model typically requires Initial Conditions (IC) and Boundary conditions (BC). For operational use, such data is generally provided by previous model runs. For model development and testing, There may still be a need for providing tools for creating IC and BC as part of the WW4 system

• Address generation of idealized IC (Issue Idealized Initial Conditions #37 ).
• Address generation of idealized BC (Issue External Boundary Conditions #38).