Refactor bugs and apps by popularity to not require slow check_done method
Use a counter object in prioritize generator (faster)
Rename working_apps and happy_users variable to avoid confusion
Do not require "Test:" prefix for strategy_chooser; no default strategy
Refactor pick_specific_from_all methods to not require slow check_done
Fix pick_random_from_specific_* methods to work without check_done
Refactor _from_random_user and _from_random_app to not need check_done
Minor tweak to pick_random_from_easiest_bugs
Remove slow check_done function
Use frozensets instead of sets for apps/users, annotate more, and remove dead code
Do not do log calculations unless log enabled
Make apps and users tuples instead of dicts
Disable log by default, eliminate redundant constant