Fixes user-reported issues and adds support for the intersects + the incremental=true parameter for intersection detection for traces and shapes.

What has been done to verify that this works as intended?

Deployed on dev, successfully converted intersects_function.xlsx

Why is this the best possible solution? Were any other approaches considered?

No real alternatives here, we need to upgrade!

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

See XLSForm/pyxform#811

Does this change require updates to documentation? If so, please file an issue here and include the link below.

Issues filed.

Before submitting this PR, please make sure you have:

• branched off and targeted the next branch OR only changed documentation/infrastructure (master is stable and used in production)
• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced