lints: Make lint blocks consistent and ensure they stay that way
- Make maint/add_warning use the standard "magic comment marker" approach to find the lint block;
- Have it completely replace that block when run. So now it can add and remove lint adjustments.
- Make all the lint blocks everywhere the same, except for the deliberate exceptions.
- Add it to CI so it stays that way
Closes #469 (closed)
Edited by Ian Jackson