Add script with optimization functions

[MaxGhenis]

@nikhilwoodruff @DeepakSingh98 fyi loss_metrics(reform_sim) will produce these metrics as a Series:

• loser_share
• losses
• mean_pct_loss
• mean_pct_loss_pwd2 (double loss for pwd)
• reform_gini

Fixes #10

[nikhilwoodruff]

I merged your changes onto my fork and got the function working in #16