UI consistency: allow --force for where -f means force

UI consistency: allow --force for where -f means force

git branch, checkout, clean, mv and tag all have an option -f to override
certain checks.  This patch makes them accept the long option --force as
a synonym.

While we're at it, document that checkout support --quiet as synonym for
its short option -q.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>