We had a large number of classes, functions, modules, and parameters

that have been marked as deprecated, some for a very long time. This

change removes all these deprecated pieces of code.
Some parts of the codebase were still making use of the deprecated

functionality, so they've been updated accordingly.
There's a couple of template tag libraries that weren't themselves

marked as deprecated. These are the datagrids and integrations

template tag libraries. They're now empty, but we're keeping them around

for now.

Unit tests pass.