use click instead of mousedown so we dont break drag and drop support

Author: ivaynberg

select2.js

@@ -2399,7 +2399,7 @@ the specific language governing permissions and limitations under the Apache Lic
             this.selection = selection = this.container.find(selector);
 
             var _this = this;
-            this.selection.on("mousedown", ".select2-search-choice", function (e) {
+            this.selection.on("click", ".select2-search-choice", function (e) {
                 //killEvent(e);
                 _this.search[0].focus();
                 _this.selectChoice($(this));