We already had part of the plumbing for other canvas manipulations, so
this is somewhat simplified.
This excludes the interface as that is breaking the build at this stage.
Some more research is required.
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.
