Remove removed! methods from b8ad6d1.
Remove vestigal result_message from Dep (gone with #met/#unmet logging helpers).
Collapse #run_met_task into #process_met_task now some unused logging is removed.
Collapse #process_met_task into #process_self -- it's not required anymore.
Rename Dep#process_task to #invoke, to match DepDefiner.
Extract meeting logic from #process_self into #meet_dep, which mirrors #process_tree.
Rename the methods that handle the met/meet logic.
Merge branch 'met-meet-refactor'