git-notes: fix printing of multi-line notes

git-notes: fix printing of multi-line notes

The line length was read from the same position every time,
causing mangled output when printing notes with multiple lines.

Also, adding new-line manually for each line ensures that we
get a new-line between commits, matching git-log for commits
without notes.

Signed-off-by: Tor Arne Vestbø <tavestbo@trolltech.com>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>