Since keypress is no longer triggered on all keypresses in content,
the spellchecker would potentially not be triggered when it should be.
This changes the trigger to keydown, instead.
No behavioral changes otherwise.
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
