There seems to be a lot of posts in the forum asking how to align the 0 values of multiple y axes.
My thoughts for implementing this:
Chart level option (like alignTicks): alignBaseline: boolean (default: true)
Axis level option: baseline:(numeric) (default: 0)
By default 0 is the baseline for each axis, and by default the 0 value for each axis is aligned.
The user can set the baseline to any other set of numbers that should be aligned, or turn off alignment.