Change Vertical World Size to [-127, 255] (was [-63, 319])

What:

Change the world minimum y-value to y=-127 and the maximum to y=255 (was -63 to 319).

Change the sea level to y=0 (was y=63).

Note: this would NOT change total world height.

Why?

In real life, sea level has an elevation of 0 meters. A negative elevation means below sea level, and a positive elevation means above sea level.

It makes sense that Minecraft would function similarly.