Added signal light for receiving radio message

Button.cpp

@@ -159,3 +159,9 @@ TButton::play() {
     if( m_state == true ) { m_soundfxincrease.play(); }
     else                  { m_soundfxdecrease.play(); }
 }
+
+void
+TButton::gain(float new_volume) {
+	m_soundfxincrease.gain(new_volume);
+	m_soundfxdecrease.gain(new_volume);
+}