• renamed predict_is_starting() to _predict because i find the former unintuitive
• made _predict() return a TraversalId instead of &Traversal because most users were just taking the ID of the latter
• this also made the lifetimes less restrictive so _predict() can now take self, and it's wrapper funcs (predict_starting & predict) no longer have duplicated destructuring code
• match_term() has also been made to return an ID for the same reason, which also had a similar loosening effect on the lifetimes and allowed me to remove that inner function workaround
• i also lifted a single line outside of the main match statement in earley(), making it a tad less verbose

...and that's about it for now