Don't modify <title> element when is_404()

Fixes #5257

Props henrywright

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7612 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Pass $item_id and $secondary_item_id to message notification filters

Fixes #5263

Props henrywright

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7613 cdf35c40-ae34-48e0-9cc9-0c9da1808c22