Introduce an API to refresh a livetable

Refreshing a livetable from javascript is a frequent need. However we don't have an API for that, so developers write:

var end = livetable.limit;
var start = Math.max(livetable.lastOffset, 1); 
livetable.clearCache();
livetable.getRows(start, end, start, end); 

(example coming from http://markmail.org/message/3snpauu2efjmz2iu)

It would be better to have a method called refresh().