* Split off ultimate base class FileRepo from FSRepo

* Split off ultimate base class FileRepo from FSRepo
* Use rawurlencode() for paths instead of urlencode()
* Moved functionality of LocalFile::loadFromFile() to a public static function. This allows Special:Upload to entirely avoid loading metadata from the (potentially remote) store. Changed purgeMetadataCache() to use loadFromDB() instead of loadFromFile().
* Redefined private virtual URLs, giving them a repo name component instead of a host.
* Moved is_writable($wgUploadDirectory) in SpecialUpload.php to the repo
* Added some filename validation to the FSRepo's store/publish
* Changed store and publish to use relative destinations instead of absolute, as was documented
* Deprecated File::recordUpload()! Now use upload() to do both publish and record. Moved the UI bits to SpecialUpload.
* Create a null revision on reupload
* Changed most of the member variable names in UploadForm. $this->mUpload followed by some ambiguous word or abbreviation was not a good naming convention. Also did some reformatting and assorted code cleanup.