Expand OpenFAST Python interface for external inputs and coupling

[rafmudaf]

Feature or improvement description Adds a python interface for the routines used to couple SOWFA.

Impacted areas of the software The Python interface to OpenFAST Library

Additional supporting information (Taken from #24) There is still a bug I have not been able to fix: I added some write(,) statements in initi_OpFM. When they are there, everything is fine, when I remove them I get segmentation faults. They can be moved around a bit, but not too much. I don't understand why, help would be much appreciated.