The inspector now supports converting degrees to radians automatically when
using the `radians` hint, so all those utility bindings were redundant.
This cleans things up by making these properties with slash properly bound
to `set_param`/`get_param` which the users can call with the relevant enum.
This makes it easier to spot syntax errors when editing the
class reference. The schema is referenced locally so validation
can still work offline.
Each class XML's schema conformance is also checked on GitHub Actions.
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
