Calculating ZIP-234 pre-defined activation height.

[shielded-nate]

I made a last-minute edit to ZIP-234 with these changes:

• make it a goal to have the "smallest delta" of per-block issuance between the current status quo issuance vs the new ZIP-234 issuance.
• define the activation height as a "TBD" pre-calculated height trying to achieve the above goal during the third halving cycle.
• argues for ignoring any burns prior to that activation by suggesting the amount of change to issuance even for substantial burns would be relatively small (and incorporating them would require some kind of "dynamic" activation height).

I spend a bit of time trying to calculate the proper activation height based on modifying the old zec-issuance-plots repository to detect heights where the status quo issuance and the ZIP-234 curves cross each other (which they do at each halving and in "the middle" of each halving cycle). (All of the following ignores any potential burnt ZEC impact.)

The calculated results currently from that modification is:

• Height 3518072 is the first height between the second and third halving where NU5-style issuance (current status quo) becomes larger than ZIP-234 issuance.
• It claimes the second halving is at height 2726400, and the third is at 4406400. Can I get more help verifying those are correct?

Because this whole codebase is a from-scratch simulation of issuance, I want more verification that this should be the correct activation height. (Code reviews welcome, but... it's a bit messy.)

It would also help if others could do their own independent calculation of what that target height should be and see if the different methods agree.

Edit: I originally pasted the wrong crossover height (although the linked comment shows the literal output). I corrected that value.