Added a new game mode "Puzzle Rush"

We've just added a new game mode "Puzzle Rush":

In this new game mode, you have to solve the maximum number of puzzles in the predefined time limit you set (between 1 and 3 minutes)

86 level were created for this game mode, have fun!

NB: The levels in this game mode are really, really difficult. We plan to make the levels increasingly difficult (starting from easy levels) in a future update.