Move most of the code from 'for-each-ref' to 'ref-filter' to make
it publicly available to other commands, this is to unify the code
of 'tag -l', 'branch -l' and 'for-each-ref' so that they can share
their implementations with each other.
Add 'ref-filter' to the Makefile, this completes the movement of code
from 'for-each-ref' to 'ref-filter'.
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
