Numerical errors in Optimizer

[sklbancor]

Reopens #561

The PR 28 in the Optimizer repo introduces Optimizer code that should allow pinpointing where the errors mentioned in #561 happen. Please run in the relevant notebooks and report back.

@barakman

once things are a bit more quiet, I have reopened the numerical issue; I have added code to the Optimizer (in a specific branch) that should raise when those issues occur. Please run the FastLane bot tests that produce the warnings on your side and report back.