free mainpanel on reload (it is not disposed by java GC for some reason)

src/com/jpexs/decompiler/flash/gui/MainFrameRibbon.java

@@ -173,6 +173,7 @@ public final class MainFrameRibbon extends AppRibbonFrame {
     public void dispose() {
         removeAll();
         mainMenu.dispose();
+        panel.dispose();
         super.dispose();
     }
 }