Fill in missing reasons

[ScriptRaccoon]

For some properties and non-properties, there is no reason yet in the database. See https://catdat.app/missing (Categories with properties without recorded reason / Categories with non-properties without recorded reason).

1. Find reasons for all properties. (This is almost done already.)
2. Find reasons for all non-properties. (This is harder.)
3. If a proof cannot be found, simply remove the property from the category. Then it is unknown. That's life I guess.
4. When all reasons are filled, change the database schema and make reasons mandatory. (This has already been done before with the special morphisms.) This way, future entries will always need a reason. Conjectured properties (and non-properties) can be left as comments in the comments table.