Check coverage with tarpaulin

README: Add link to a nice asciinema demo (or a gif)

Handle backslash (for latex, C, and the rest)

Filter mode (read stdin, write stdout)

Skip bottom part when checking commit messages

Generic Repo tests to reduce duplication between FakeRepo and Db

`kak-spell enable` should run kak-spell on all open buffers

Implement `kak-spell-next`, `kak-spell-previous`