mediawiki.Uri: Use extended RegExps through templates

mediawiki.Uri: Use extended RegExps through templates

JavaScript does not support the 'x' RegExp option for 'extended'
RegExps, or named capturing groups, which makes it impossible to write
large RegExps in a readable way. OR DOES IT?!?

Cons:
* Small runtime performance loss to convert to regular RegExp
* Worse minification due to unminifiable whitespace
    (Both of these problems could probably me resolved
     if we moved the processing server-side somehow,
     but there's no support for it in ResourceLoader now)

Pros:
* You can actually somewhat understand the bloody things if you care
  to, unlike before.

YMMV:
* The actual regexps are in different files

Change-Id: I41630bf20cdb5c2936d85d9f831f2aa7bb8cfef1