Enable rectangular members in wisdem and connect to raft

[yqliaohk]

Purpose

This PR enables the parametrization of rectangular members and the related parameters to propagate from wisdem to raft. An example is added. This PR requires the updates in wisdem and raft (https://github.com/WISDEM/RAFT/pull/51) to run.

Type of change

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] 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

Explain the steps needed to test the new code to verify that it does indeed address the issue and produce the expected behavior.

Checklist

• [ ] I have run existing tests which pass locally with my changes
• [x] I have added new tests or examples that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[gbarter]

Closing because this branch has been merged into release_prep