git-remote: list branches in vertical lists

git-remote: list branches in vertical lists

Previously, branches were listed on a single line in each section. But
if there are many branches, then horizontal, line-wrapped lists are very
inconvenient to scan for a human. This makes the lists vertical, i.e one
branch per line is printed.

Since "git remote" is porcelain, we can easily make this
backwards-incompatible change.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>