The underscore prefix was used to avoid the conflict between the `RID` class
name and the matching enum value in `Variant::Type`.
This can be fixed differently by prefixing uses of the `RID` class in `Variant`
with the scope resolution operator, as done already for `AABB`.
It's too hard to get compatibility between GNU and BSD sed,
so let's just use perl oneliners.
And improve it to also remove trailing tabs, not just spaces.
