facebook: fix for safe_image external images and logged-out profile icons.

Don't attempt profile pic when don't have username, eg on cover photo pic page when logged out
facebook: fixed cover photo at top of profile
facebook: fixed to work with photos when viewing mobile site
facebook: now shows pop-up for profile icons even when logged out.

Due to structure of facebook's html, when logged out pop-ups
come from the profile icon itself rather than the profile
icon in the hovercard (though it comes from there too for
users whose hovercard links to their profile, which may
depend on their visibility settings).

Also removed dead code.
Version 3.2beta12