Allow hgweb to search for templates in more than one path.
This patch is constructed to make it easy for external extensions to
provide their own templates, by updating templater.path.
bdiff: normalize the diff (
issue1295)
When the common part of a diff can be moved forward, move it forward.
Otherwise we don't get deterministic results (it would depends on the way we
split for the recursion).
That way we get identical hunks when doing the same change, it helps to solve
issue1295 (inconsistent diffs on different side during a merge).