Fix directionality of translator comments

Now the comment is set to RTL or LTR independent of the UI language
using jquery.bidi.

The text alignment still follows that of the UI, though. Fixing that
will require putting the comment on a paragraph of its own.
Fix directionality of user suggestions

Similar to translator comments in the previous commit.
Fix directionality of timeline items

* timeline-field-3 are UI strings, so they should just use main language
  and direction, which allows us to set the correct arrow as well.
* the others are user input, so we use jquery.bidi.
Various fixes to Wikipedia lightbox

* force the iframe to consume all the width
* prevent horizontal scrollbar when direction is RTL
* move close button to the left when direction is RTL
Just use the clipping method