Improve mediaWiki.parser() (which is a very strange name for a function that expands...

Improve mediaWiki.parser() (which is a very strange name for a function that expands $1, $2, ... in i18n messages) to use .replace() with a callback, so it will handle edge cases like more than 9 parameters ($10 would be treated as $1 followed by a literal 0) or a parameter's value containing $n (which would then get substituted again). Code written by Neil Kandalgaonkar and trivially modified by me.