Achievements UI. #65
Game-count achievements. #65
Achievement popup animation. #65
Achievements show their popup when achieved - multiple times. #65
Achievement description; main menu text. #65
Show achievement popups once and only once. #65
Achievement list reports up-to-date data. #65
Back button works from highscore and achievement screens. #65
Achievement sound effects... sort of. Pause breaks it. #65
Timescale not used on gameover screen anymore, so achievement popup isn't "paused". #65