Add optimal bet spread calculation

[mhluska]

Currently we're able to manually define the bet spread or use a simple exponential spread (e.g. TC 1 $10, TC 2 $20, TC 3 $40 etc.). It would be nice if there was a command to return the optimal spread given table conditions. As well as using the optimal one by default for simulations if a custom one isn't provided.

[mhluska]

This is getting us more on the right track: 44bf9bd

We want a spread that linearly scales with the advantage. But this currently makes the assumption that at TC 1 we have 0% advantage. That might not be true given certain table rules and deck counts. How can we estimate house edge irrespective of bet spread?

It's kind of circular - in order to simulate house edge, we need to spread. But to find the optimal spread, we need the house edge.

One idea is just run the simulation first with no bet spread or counting. Just basic strategy. Then we can figure out at what TC we have an advantage (given 0.5% per TC).