[PATCH] Language selection based on browser preference, use UTF-8, care about direction, etc

Hello,

Attached patch:

* Picks a language based on the actual browser preference.
* Makes all pages default to UTF-8.
* Adds language direction support.
* Makes pages tell the browser what language they're in.
* Fixes language_map.
* Adds a couple of extra handy language functions.

It's in place at our pgweb, but diffed against gborg. Set your browser
to 'de' (Tools -> Options -> General -> Languages, add 'German [de]' and
move it up to the top) and you'll see a german news item at the top (I
google translated it) of the homepage. Go to About/Advantages and you
should see the german version of the page from advocacy. Right-clicking
on the page and clicking 'Properties' should say "Text Language: German."

Clicking the Arabic or Hebrew on the bottom should switch the page
direction.

Omar