Integrate Plupload

The output format for "OnUploadFile" event was changed from Plain-text to JSON. Solution add new "uploader_type" optional setting to "_install/theme.xml" in theme add "UploaderType" field to "theme" unit/db table: options: swfupload - SwfUpload, plupload - Plupload default: swfupload (to preserve BC) in the "kThemesHelper::refreshTheme" method populate value of "UploaderType" field of the created theme with value of "uploader_type" setting, when found in "theme.xml" for "kUploadHelper::handle" method: add optional "$form_field" parameter, that will be set to "file" value, when not given use value given in "$form_field" parameter instead of hardcoded "file" value in this method and method it calls internally ("getUploadedFilename", "moveUploadedFile") in the "OnUploadFile" event: return results in Header+Text format (former code) when we're on Front-End and "UploaderType" theme setting is set to "swfupload" value return results in JSON format (current code) in all other cases