request: make envelopes an effect

[M0ahgra]

make envelopes an effect, for simplicity.

[Mid-The-Modder]

The issue with adding effects would be that the effect storage in the code has to be increased which could be a bit troublesome for compatibility with existing songs. That and the fact that this envelope system has kinda just. been established as the remaining one by a very big portion of communities, so making the move to turn it into an instrument effect- although sorta logicial- would be very confusing for people.