Remove 2 keyboard short cuts.

Ctrl-C & Shift-Ctrl-C were used for next & prev DC which was considered
to be poor style.

Disable for now. Maybe replace with something else?

Signed-off-by: Amit Chaudhuri <amit.k.chaudhuri@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>