Check for prior initialization of ROSCO

[dzalkind]

Description and Purpose

In some wind farm simulations, it's possible to load ROSCO twice, which produces a seg fault. This should catch that error in a more friendly way. #369

Type of change

What types of change is it?
Select the appropriate type(s) that describe this PR

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

TODO Items General:

• Add example/test for new feature
• Update registry
• Run testing

Github issues addressed, if one exists

Examples/Testing, if applicable