Added Mixer Component, and VCO Component

src/features/timbre/Timbre.js

@@ -1,11 +1,13 @@
 import React from 'react';
 import VCO from './parameters/VCO';
+import Mixer from './parameters/Mixer';
 
 export function Timbre(props) {
     return (
         <div>
             <VCO id="vco1" />
             <VCO id="vco2" />
+            <Mixer id="mixer1" />
         </div>
     );
 }