add halt function to zelib
rename add_tile to place_tile
add get_player_by_id function
add tile_exists function
add tiles_count function
use tiles_count
rename give_tile to give_tile_by_id
rename show_dominos to show_tiles
rename function view_tile to get_tile_by_id
renames functions tiles_count to count_files and simulate to ui
add functions prompt_player, get_winner and game_status