Cosmetic code changes

Use the 1- and 1+ functions instead of going to great lengths to do the
same thing much more verbosely.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Refactor the key binding code

Instead of having an unused tdd-status-map, and pretty much the same
thing duplicated to global-map, fill in tdd-status-map properly (no
prefix keys), and add the map to the global C-x t key instead.

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