Threedi-modelchecker

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- Fixed TypeError with CrossSectionShapeCheck when width/height are `None`.
- Updated some constraints on CrossSectionShapeCheck:
- Heights of tabulated shape must be increasing.
- Egg only requires a width, which must be greater than 0.
- Added 0 to a valid value for ZoomCategories. Also renamed the ZoomCategories names
to something clear names.

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- Renamed some methods of ThreediModelChecker.
- Added basic to the 3di model schema: checks if the model has the latest migration
applied and raises an error if not.
- Rewrote CrossSectionShape check to no longer use regex and added it to config.

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- Initial project structure.
- Added ORM for a threedi-model in sqlalchemy.
- Added several types of checks.
- Manually configured many checks.
- Added check factories, which generate many checks based on the ORM.