Final 4 conds; reload after error in training

1. (experiment.js, jspsych-scmvar.js) reload instead of continue on
incorrect answers during training; feedback modified appropriately
2. (experiment.js) added code for 4 conditions: nonvaried, adaptive
variation, yoked varied, yoked shuffled (other conditions eg adaptive
retirement deleted)
3. (experiment.js) question lists are passed as params to question
selector constructor instead of being created by it; indexing instead of
popping is used to keep track of where we are in the question list
4. (experiment.js, demo.html) yoking sequence is passed in to
makeExpStruct call and handled appropriately
5. deleted some leftover stuff in experiment.js mostly involving
OAPlc/ROAPlc variation