Task: Uncertain reference R&A

[shippy]

Citing from my comment on #62:

• a risk and ambiguity task with choice between 2 lotteries
  • This renders choseLottery meaningless, and requires the choice fields to be reliable. (Which it should, but see Reversed probability level reporting #115.)
  • drawLotto relies on offCenterByPx set in the configuration file. It does not assume that the same configuration file could want to call it with different off-center values. In other words, this might require implementing Draw scripts should take position as an argument #98.
  • drawLotto & generateTrials assume that there is exactly one winning payoff, and possibly that there is a reference. This might require refactoring.