Turn the package into two minor modes

Instead of fiddling with mode-line-misc-info and the global key
bindings, turn the package into two minor modes: one for buffer-local
operation, one for global mode.

Together with the previous commit, this fixes #4.

Requested-by: Steve Purcell <steve@sanityinc.com>
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Use standard emacs functions instead of cl-lib.

There is no cl-lib in Emacs 23, cl is far too big, and we only used two
functions out of it anyway, which are easily replaced by standard
functions.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Revert "Don't test with Emacs23, it doesn't work"

This reverts commit 7c8d4396ef98c4372e852142a0825a0113ee99a2.
Ignore t/ert.*

t/ert.* are downloaded during testing, ignore them.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
README.md: Cosmetic update

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>