Pause menu improvements

Hi there.

Now the pause menu screen has sound effects on it! A lot more pleasant (:

And also the level selection system has been improved. Now you can select the level by its number and then press A (gamepad) or Enter (keyboard) to go to the level you have selected. You can also fast forward the numbers on the level selection by holding the arrow key.

Thank you all and I hope you are enjoying the challenges at Mastho is Together :D