Adding powercurve actuator method

[cfrontin]

Purpose

This PR integrates the actuator disk method with power curves enabled.

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)

Testing

I've run some stuff verifying that an isolated turbine recreates the theoretical powercurve (i.e. P=Prated above Vrated, CP-maximization at the lowest range, power limited s.t. T=Tmax in thrust shaving region, etc.)

We should probably make a formal test of this behavior!

I think we probably should add smooth cutoff emulation as well?

Checklist

Put an x in the boxes that apply.

• I have run existing tests which pass locally with my changes
• I have added new tests or examples that prove my fix is effective or that my feature works
• I have verified my code additions work in parallel
• I have added necessary documentation