Fix onsets. Set to word onset not fixation onset

Fix idx.allTrialOns, so that it aligns with the onset of the word
(memory cue), rather than the onset of fixation. Add
idx.alltrialons_fixation and idx.alltrialons_prompt.

logfile_check cursory check for discrepancies between handmade onsets
files and idx outputs from LTLab_fMRIBehAnalysis_Ret. A similar thing
may need to be done once mvpa_ons are created.
add abstraction to univariate processing

Add functions to make onsets and motion regressors for the univariate processing stream.
add contrasts to analysisByPerfAndPhase