Reorganize the repo

[ewu63]

Purpose

I split the original pySpline file into four additional files

• pyCurve
• pySurface
• pyVolume
• utils

I also:

• renamed numpy to np
• reordered some imports
• added separate docs pages for each file

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)
• [x] Refactoring (no functional changes, no API changes)
• [ ] Documentation update
• [x] Maintenance update
• [ ] Other (please describe)

Testing

All existing tests pass

Checklist

Put an x in the boxes that apply.

• [x] I have run flake8 and black to make sure the code adheres to PEP-8 and is consistently formatted
• [x] I have run unit and regression tests which pass locally with my changes
• [ ] I have added new tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[ewu63]

I just realized that this is bad because I didn't preserve line history for almost the entire repo. Supposedly that is possible so I'm going to work on that approach instead.

[bernardopacini]

I just realized that this is bad because I didn't preserve line history for almost the entire repo. Supposedly that is possible so I'm going to work on that approach instead.

I had to go through this exact process on a smaller scale while splitting files earlier today. Let me know if you'd like help.