gitweb: Use href(-replay=>1,...) for formats links in "commitdiff"

gitweb: Use href(-replay=>1,...) for formats links in "commitdiff"

Use href(-replay->1,...) in (sub)navigation links (like changing style
of view, or going to parent commit) so that extra options are
preserved.

This is needed so clicking on such (sub)navigation link would preserve
style of diff; for example when using "side-by-side" diff style then
going to parent commit would now also use this style.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>