Remove the superfluous hook

Minor modes from `define-minor-mode` automatically run a -mode-hook.
Make variables customizable
Remove the PKG file
Add alias for the old hook variable

Follow up to 3109fe9
Merge branch 'no-pkg-file'
Add test to make sure we support the old hook name.
Merge branch 'custom-interface'
Update to version v0.7.2.