重构tree方法新加（接上篇）清除tree缓存

      clear:function(jq){
                                                              return jq.each(function(oj){
                                                              var tree=$.data(this,"tree").tree;
                                                              tree.find("div.tree-node-selected").removeClass("tree-node-selected");
                                                              var cc=tree.tree("getChecked");
                                                             for(var i=0;i<cc.length;i++){
                                                                   tree.tree("uncheck",cc[i].target);
                                                                     }
                                                          });//可直接拷贝，无需改动。用法如下：

                                                                 $('#treeid').tree("clear");