Support Update(ESP8266 and ATmega32u4 and Mega2560) and other cool stuff

MusicWithoutDelay v3.5.0

Features Update

• Added support for multiple boards including esp8266, atmega32u4, the MEGA2560(which used to be broken since 2011)
• Created Stereo support
  • The Teensy has multi-stereo
• Added option to increase note polyphony(the only limitation is your microcontroller's processor speed)

New Bugs

• Unfortunately, some songs don't work on the esp8266. 😢 It has to do with i2s, but I don't know how to fix it.
  • It makes a high pitch sound while playing.

Other Changes

• I changed the maximum for setVolume() to 127.
  • (0 to 127)