Start ADC HPATimer only once. Makes for more stable collection of audio

when connected to wifi (especially station mode). However the range of
output from the ADC is truncated.
TODO fix, or use system_adc_fast_read with wifi off and RF off
The devfixes branch of esp82xx needs to be used

embedded8266/user/user_main.c

@@ -131,6 +131,7 @@ static void ICACHE_FLASH_ATTR myTimer(void *arg)
 	{
 		StartHPATimer(); //Init the high speed  ADC timer.
 		hpa_running = 1;
+		hpa_is_paused_for_wifi = 0; // only need to do once prevents unstable ADC
 	}
 //	uart0_sendStr(".");
 //	printf( "%d/%d\n",soundtail,soundhead );
@@ -222,6 +223,12 @@ void ICACHE_FLASH_ATTR user_init(void)
 
 	ws2812_init();
 
+	// Attempt to make ADC more stable
+	// https://github.com/esp8266/Arduino/issues/2070
+	// see peripherals https://espressif.com/en/support/explore/faq
+	//wifi_set_sleep_type(NONE_SLEEP_T); // on its own stopped wifi working
+	//wifi_fpm_set_sleep_type(NONE_SLEEP_T); // with this seemed no difference
+
 	system_os_post(procTaskPrio, 0, 0 );
 }