hgweb: add a 'linerange' parameter to webutil.diffs() This is used to filter out hunks based on their range (with respect to 'node2' for patch.diffhunks() call, i.e. 'ctx' for webutil.diffs()). This is the simplest way to filter diff hunks, here done on server side. Later on, it might be interesting to perform this filtering on client side and expose a "toggle" action to alternate between full and filtered diff.