Implement global file/directory change watch service & implement it for the file-browser.
Includes inline-watch upon filecount/filelist if a watch_id is given. The watch handels are identified by window_id, view_id (both set automatically) and watch_id of choice. Upon changes a "watch" message will be send via bus containing further details (action, watched path, watch_id). Also prevent multiple filelist updates from running simultaneously and improve overall update triggering.