Trading cards, controls and training section! Update #1

This one contains what most people wanted, more information about controls and some tweaks that aren't very important but still good. Remember that any suggestion or bug report can be made. - Added trading cards - Finished Training mode. - Better training mode with small tutorial included in every note (like controls) - New texts on loading section - Better looking on difficulty menu and others - Added "Change player" controls in Options > Controls menu - Added new sprite, the ball launcher machine, in the training (for Goalkeepers) and more difficulty