Add play simple tone sequence function

[zenodante]

Current a sound updating is only possible in update() with 25ms step. However, when porting games from other system sometimes we need play much faster changed tone sequences. How about add a api function like PlaySimpleTones(uint16_t *seq, uint32_t volume) and a bool state to tell the sound updating callback to switch between normal sound or simple tone state? The Sequence could be a 16bit uint array [xxxhz,yyyyms,xxxxhz,yyyyyms], then we could have easy to use sound effects.

[zenodante]

I found the solution to do it without changing the API... Just disable the 1ms sound update callback and replace it with my own one...