* Introduced a non-dummy collation for $wgCategoryCollation, namely UCA with default...

* Introduced a non-dummy collation for $wgCategoryCollation, namely UCA with default tables.
* Added a maintenance script which generates a list of first letters. Unified Han are omitted for performance, and because they shouldn't be used as headings anyway. A future collation specific to Chinese would provide the KangXi radicals as "first letters".
* Provided a precomputed list of first letters. Used Unicode 6.0.0 data and ICU 4.2.
* Moved collation functionality from Language to a Collation class hierarchy with factory function. Removed the recently-added methods from Language and updated all callers.
* Changed Title::getCategorySortkey() to separate its parts with a line break instead of a null character. All collations supported by the intl extension ignore the null character, i.e. "ab" == "a\0b". It would have required a lot of hacking to make it work.
* Fixed the uppercase collation to handle non-ASCII characters, redundantly with r80436. I don't think it's necessary to change the collation name as was done there, so I reverted that in the course of my conflict merge. A --force option to updateCollation.php might be nice though.