Make handleButtonPress virtual.

Author: synthead

src/Watchy.h

@@ -52,7 +52,7 @@ class Watchy {
   float getBatteryVoltage();
   void vibMotor(uint8_t intervalMs = 100, uint8_t length = 20);
 
-  void handleButtonPress();
+  virtual void handleButtonPress();
   void showMenu(byte menuIndex, bool partialRefresh);
   void showFastMenu(byte menuIndex);
   void showAbout();