Psifr 0.8.0

This version adds analyses to examine transition statistics based on items recalled before the just-recalled item.

• Added fr.lag_crp_compound to measure conditional response probability based on the lag of both the previous and current transition.
• Added fr.distance_rank_shifted to test whether transitions reflect distance to items recalled in earlier output positions.
• A new tool, transitions.sequences_masker, to help with analyses examining sequences of multiple transitions.