Best times and cover art

I have been working mostly on doing cover art for the game as well as a gameplay trailer, but I do have some new stuff done.

-added best time for each level : your fastest time on a level is now saved and displayed on the worldmap. Since this is the playable online version, the save will disappear as soon as you close the window, but in the final game it will be permanent. 

-added shortcut p to pause/unpause.

-new title sprite

-updated a few sprites (bubbles) and a music

-minor tweaks and fixes