TIC-Sweeper 0.6 update

Changelog

0.6

• updated to TIC-80 0.28.0
• fixed minutes timer display in interface showing a leading 0 from 60 to 69
• added preventing flagged tiles to be revealed in check_adjacent()
• added not manually revealing flagged tiles
• added press X to hide win/gameover textbox
• added X and Y to the controls menu
• added button navigation display in menus
• added button icons in endgame textboxes
• tightened code indentation
• refactored difficulty{} table and simplified init_game(), update_ and draw_menu(), and menu_controls()
• added ingame music on/off in menu