Mark plural strings for translation. Unfold each action case in one
entire sentence.
Pass new keyword for xgettext to extract.
Update test to include new subroutine __n() for plural strings handling.
Update documentation to include a description of the new __n()
subroutine.
Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>