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.
Merge pull request #2191 from glassez/webui

WebUI: Implement server-side filtering, sorting and limit/offset.
Follow project coding style. Issue #2192.
WebUI: Fix increasing frequency of XHR requests

ajaxfn() is called every time the torrent list is filtered. This function
calls itself after a predefined amount of time by setting a timer. If
the function is called manually without destroying the timer, the
frequency of the XHR requests will increase.

Fix this by saving a reference to each timer that is created so that
they can be later destroyed.

Add also two helper functions to request updated data safely.
WebUI: Update title immediately when showing/hiding rates
WebUI: Keep current preference for the title style in a variable

Read persistent value only when required.
WebUI: Remove unused variable
WebUI: Use CSS to alternate row colors in transferlist

Keep the old code for IE < 9, the majority of the browsers
shouldn't need it.

Also, keep the CSS code in one place.
Merge pull request #2224 from pmzqla/webui-updates

WebUI changes
Sync translations from Transifex and run lupdate.