ugly fix to greedy opening of all cells when clicking on empty
udpates "checkIfWon" function to win if all non-mine cells are open

Previous also checked that all mines are marked, which appeared to be unncessessary according to the rules
Game Menu to start "New Game" on a field of given size
Initial version of dynamic adjustment of field width and "game status smiley" positioning
moves counter number implementation
implements "timer" functionality
styles are calculated dynamically by passing 'cellWidth' to Game
starting timer after 1st click
styling moves counter and timer