Added ESP32 interrupt based buffer feeding

[juergenpabel]

This PR is the continuation of PR #73, which I had to close because I had already deleted that repository from which the PR originated.

I ported the patch to a newly forked repository and created this PR; because I don't have a VS1053 based dev setup anymore at hand, I didn't even test whether this change even compiles (it looks OK from just staring at it).

[MarcHagen]

I'm struggling to get this working, my sound comes out popping and "slowed".

Also it is not async, the main loops still hangs doing feedBuffer.

Adafruit_VS1053_Library/Adafruit_VS1053.cpp

Lines 276 to 286 in b44b1e1

	// wait till its ready for data
	while (!readyForData()) {
	#if defined(ESP8266)
	ESP.wdtFeed();
	#endif
	}
	// fill it up!
	while (playingMusic && readyForData()) {
	feedBuffer();
	}

maybe using this PR would help, #39

So what is the advantage?

[juergenpabel]

I'm struggling to get this working, my sound comes out popping and "slowed".

Also it is not async, the main loops still hangs doing feedBuffer.

Adafruit_VS1053_Library/Adafruit_VS1053.cpp

Lines 276 to 286 in b44b1e1

	// wait till its ready for data
	while (!readyForData()) {
	#if defined(ESP8266)
	ESP.wdtFeed();
	#endif
	}
	// fill it up!
	while (playingMusic && readyForData()) {
	feedBuffer();
	}

maybe using this PR would help, #39

So what is the advantage?

As far as I remember (this part of some project I did was 2-3 years ago, I just recreated the PR this year) - the PR offloads buffer feeding onto the 2nd core of the ESP32 (thus relieving the 1st core from calling the feedbuffer inside loop()). My project was working flawless on at least the huzzah32 (and if I remember correctly also on the dfrobot esp32 board).

I have no clue what issue you're experiencing, sorry.

[WoutStandaert]

This addition works for me on the Feather ESP32 v2. I think it should be merged.