WebUI: Improve btjson.* indentation.
Implement QTorrentHandle torrentState() and eta().
WebUI: Implement server-side torrent filtering.
Use QTorrentHandle::torrentState() in btjson.
WebUI: Fix indentation.

Fix indentation in client.js and dynamicTable.js.
WebUI: Drop client-side filtering.
WebUI: Fix transferlist.html indentation.
WebUI: Implement server-side sorting.
WebUI: Implement limit/offset.
WebUI: Drop client-side sorting.