* (bug 18011) Special:FileDuplicateSearch UI fixes and remote file repo support

* (bug 18011) Special:FileDuplicateSearch UI fixes and remote file repo support

Fixes:
- now accepts file titles with or without File: prefix instead of demanding you must remove it
- moved result summary line from bottom to top
- added a line telling you no file was found if it wasn't found
- now pulls the reference file's SHA-1 via FileRepo, so can give it a remote file (eg from Commons)
- now pulls duplicate files via the main RepoGroup instead of querying image table manually, so turns up remote duplicates
- dropped the QueryPage standard paging header/footer; file dupe lists are usually very short and it's not worth copying the infrastructure

To make this work, I switched the special page class from using the standard QueryPage paths to doing the query and list itself; QueryPage is currently very tightly tied in to database queries, and doesn't provide a very clean way to drop in an alternative way of looking stuff up (say an API query or just getting a big array you've gotten from somewhere). If that gets improved, this page should be cleaned up to use more of the QueryPage infrastructure again so it's pretty and doesn't scare people coming in to maintain it.

Localization changes:
- added fileduplicatesearch-noresults message
- changed fileduplicatesearch-summary in English master to remove the supplementary line about taking out the 'File:' prefix