Refine risky food sim to implement risk types

[rlskoeser]

RISKY-FOOD-TYPES
Start with 11 “risk types”--0, 0.1, 0.2, 0.3, …, 1
Begin the game with 110 agents, 10 of each type
Do the procedure as we have it (food the same, choice the same, etc.)
Only thing we’re changing is how next round is populated
#of type on next round = #this-round x payoff of type this round / 2
For example, the 0.1 type goes for SAFE and gets payoff 2. There are 10 of them this round
Next round: 10 x 2 / 2 = 10
The 0.9 type goes for RISKY and gets payoff 1. There are 15 of them this round
Next round: 15 x 1 / 2 = 7.5 [round off? Randomly round off?]

To avoid rounding:
Start with 16 agents of each type; payoffs are 1, 2, 4.

[rlskoeser]

implemented in #12; reviewed in meeting 7/24