draft Curved ob

[henryg7vdj]

Briefly, what does this PR introduce?

First attempt to model curved silicon surfaces on the OB staves. Not yet working. See README for details.

What kind of change does this PR introduce?

• [ ] Bug fix (issue #__)
• [x ] New feature (issue #__)
• [ ] Documentation update
• [ ] Other: __

Please check if this PR fulfills the following:

• [ ] Tests for the changes have been added
• [ ] Documentation has been added / updated
• [ ] Changes have been communicated to collaborators

Does this PR introduce breaking changes? What changes might users need to make to their code?

Does this PR change default behavior?