Add code for switching the speaker respective their amps on or off.

include/player.h

@@ -62,6 +62,8 @@ private:
 	void _unmute();
 	void _sleep();
 	void _wakeup();
+	void _speaker_off();
+	void _speaker_on();
 
 	SPISettings _spi_settings_slow = SPISettings(250000, MSBFIRST, SPI_MODE0);
 	SPISettings _spi_settings_fast = SPISettings(4000000, MSBFIRST, SPI_MODE0);