Make the floating title transition smoother

Previously the floating title would not appear until the real title
scrolled entirely out of view, which was visually distracting.  Now it
appears at the point when its bottom lines up with the real title’s
bottom.  This isn’t perfect yet due to small differences between the
two titles’ layouts, but it’s much closer.

We now need to use visibility: visible|hidden instead of display:
block|none to show and hide the floating title, in order to be able to
retrieve its height while it’s hidden.  It’s important to use that
height because occasionally line wrapping differences make the
floating title shorter than the real title, and we don’t want the real
title to poke out from underneath.

Also fix scrollToRowId to offset by the 4 pixel top margin (like
cdmScrollToArticleId already does), so that it goes back to a point
when the floating title was hidden; and set the right margin on the
floating title so that it’s the same width as the real title and
doesn’t overlap the scroll bar.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

feedparser: xpath doesn't properly query for title element if there's a default namespace so let's add a separate ugly hack for rdf:RDF feeds, thanks for that xml dipshits

Updated FeedItem_RSS::get_title()

Reverts most of be60340c. Implements a simplier solution using XPath to get the proper title tag from a feed item.

Temporarily enable entity loader when importing XML file.

rebase translations, update script to maybe extract more translations from js files (fuck you xgettext you piece of shit)

Drop duplicate database indexes

These duplicate indexes were found by the pt-duplicate-key-checker
tool in percona-toolkit.  Duplicate indexes waste space and slow down
the query planner.  Closes #835.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

af_comics_dilbert: fix for new dilbert.com shenanigans