New release announcement style "Westin" by shadowm and vultraz

This is a work-in-progress modern announcement style intended to replace
the dated Glamdrol style. It is not quite finished (the large intro
background is a headache due to its sheer size and alignment issues),
but it's expected to be complete in a few days.

Some of the most important changes:

 * There is no TOC anymore. (vultraz)
 * There is a large intro section with a background picture and words
   and a text-less shield logo (vultraz/shadowm).
 * Big image button with a link to the downloads section. (vultraz)
 * Animated scroll from download button. (shadowm)
 * Gradients, gradients everywhere. (shadowm)
 * Some styles are overridden on small display devices. (shadowm)
 * There is a copyright note in the footer. (shadowm)
 * Added dependency on jQuery, might be dropped if I don't find more
   uses for jQuery. (shadowm)
Use apostrophes instead of quotes in HTML attributes

This is probably supposed to make things easier for translators, since
otherwise the quotes would wind up included in msgids for <a> elements,
etc.
Drop dead code
Center the 'What's new' text
Reorganize CSS rules in sections
Import glamdrol from a non-intranet location to make vultraz less upset
CSS coding style fixes
Copyright statement
Import styles and drop dependency on Glamdrol

We were only using something like 10% of the Glamdrol stylesheet, the
rest of it being mostly wiki-specific styles and other things we do not
use here (front page overview box, etc.). Since Glamdrol is so large, it
was pretty much a waste of bandwidth. And for people who normally visit
wesnoth.org and have Glamdrol cached, it still posed a problem:

 * Westin is *huge*. It @imports Glamdrol so as to block loading the
   rest of the stylesheet since things would otherwise look horribly
   broken if Glamdrol was downloaded and applied first.
 * Conversely, if Westin was loaded before Glamdrol (by <link>ing
   Glamdrol), things would look terribly broken.

Included in this commit is the Glamdrol/Monobook bullet, which is also
included inline in the stylesheet for browsers that support Base64
inline images.

Westin before and after this change is unchanged to the pixel level as
far as I an tell.
Rename intl.css to westin.css

It's no longer a mini-stylesheet with overrides for the language
selection section, but rather a whole monolithic monster of its own.
Drop language selection placeholder
Drop element-specific rule, replace it with a class specification
Check in jQuery until I decide whether to drop the dependency on it
Reworded part of the Download section
Merge branch 'master' into staging/master-to-westin-1
Add bit on new translations
Split off trailing JS to work around po4a-gettextize stupidity

po4a-gettextize believes non-empty <script> blocks are translatable, so
we get around that by including an external file instead. Since the code
in question is currently only implementing the Download scrolling
effect, this shouldn't be a major problem.
Drop redundant font candidates

No browser running on a system with Segoe UI could possibly be old
enough so as to not support web font resources.
Rearrange header bg, apply a fading border, and make section divider thinner

Rearranging the background image was necessary to make it less
conspicuously misaligned relative to the logo. Now the logo isn't
aligned to anything, but it doesn't look like it's *supposed* to be
aligned either, which is the superior option.

The image is also now rearranged on low resolutions so that there is
about as much sky visible as in the high resolution ruleset.

By applying a fading border (and the background color from the divider),
it's less conspicuous when the image gets clipped at the bottom, and the
divider can be made thinner.
Drop the problematic top area size animation rules

They expose the empty area beyond the background's extents at times,
which looks really bad.