[Mixpanel] add reset method to mixpanel global instance

types/mixpanel/index.d.ts

@@ -1,4 +1,4 @@
-// Type definitions for Mixpanel
+// Type definitions for Mixpanel for 2.11.1
 // Project: https://mixpanel.com/
 //          https://github.com/mixpanel/mixpanel-js
 // Definitions by: Knut Eirik Leira Hjelle <https://github.com/hjellek/>
@@ -24,6 +24,8 @@ interface Mixpanel
 
     register_once(params:{[index:string]:any}, defaultValue?:string, days?:number):void;
 
+    reset():void;
+
     unregister(propertyName:string):void;
 
     identify(id?:string):void;

types/mixpanel/mixpanel-tests.ts

@@ -32,6 +32,8 @@ function mixpanel_base()
     mixpanel.get_config();
 
     mixpanel.get_property('device');
+
+    mixpanel.reset();
 }
 
 function mixpanel_people()