This is a generally useful abstraction, so let's let others
make use of it. The refactoring is more or less a straight
copy; however, functions and struct members have had their
names changed to match string_list, which is the most
similar data structure.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
