Re-sort table data if __tsort_rebuild is set

Why?
I'm trying to use tsort to implement a real-time monitor system. Ajax is used to update data in the table. After updated, the old version tsort would not re-sort table.

How?
A new variable "\__tsort_rebuild"  is added to fix this. Once "__tsort_rebuild" is defined, ervery time you click the resort button(&lt;th&gt;...&lt;/th&gt;), tsort will try resort data with function "getTableData".

Code Sample

```javascript
var __tsort_rebuild = 1;
var __tsort_direction = "descending";

setInterval("autosort()",3000);

function autosort(){
    $.ajax(
        {
            .......
            error: function(){
                ....
            },
            success: function(realdata){
                ... update data in table ...
                // resort
            }
        }
    );
    $("#sorttable").find('#th_id').first().trigger('click');
}
```

Demo: [MySQL Realtime Status](http://www.orczhou.com/tsort/)