* Put float:left/right for images in shared.css with @noflip. This was inconsistent...

* Put float:left/right for images in shared.css with @noflip. This was inconsistent between skins, causing image alignment on RTL wikis to be dependent on your skin. Left is left and right is right, even for RTL languages :)
* Also moving position: relative; from all skins to shared.css
* Replacing .mw-content-ltr/rtl (added in r90743) with div#content [dir="ltr/rtl"] so it also works on e.g. special pages