Move to python-based precomp and correct specious airfoil rotations

[gbarter]

Purpose

This should solve both some of the windows Fortran frustrations in #505, by porting precomp to python, and the well-intentioned but ultimately specious airfoil rotations noted in #388.

The precomp code is broken out into its own submodule, instead of all being squashed into a single file under RotorSE.

Type of change

• 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 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 added necessary documentation