Namespace for Mouseup event and Unbinding Call

Hi,

I have added namespace for mouseup event and uncommented out code for calling unbind of mouseup. tried to uniquely identify the namespace by appending id (assuming that id is always present) cause we can have multiple jqgrid in one page and can destroy only one of them and hence making sure that unbind gets called only for that one which is getting destroyed. 

Also set "res" to null cause it was appearing in google chrome profiler in unclaimed object list.  

Thanks,
Kunal