XPath *never* return None.

(I found the HTML report of coverage)

[fix] btdigg

Change the cookie in bing_news to use the english interface

But still uses the language to set the market, and so provide relevant results to the language.
Fix #198

[fix] google engine (close #193)

Moar engines

[enh] improve response time. close #100

General cookies

Add '?' bang to the autocompleter

Russian translation

Two colors are needed so I use a space in the cookie and a split in jinja to "encode" and "decode" them.
We should enforce that each theme if they must use a cookie, prefix its name with the name of the theme.

The color proposed here are based on bootstrap. We could use others.