changed piece sprites, changed UI elements

assets/sprites/wizard.png

assets/sprites/wizard.png.import

project.godot

scenes/Assassin.tscn

scenes/King.tscn

scenes/Knight.tscn

scenes/Mage.tscn

scenes/Pawn.tscn

scenes/Queen.tscn

scenes/Wizard.tscn

scenes/game.tscn

scenes/screens/select_piece_screen.tscn

scenes/screens/title_screen.tscn

scenes/ui/pop_up_label.tscn

scenes/ui/ui.tscn

scripts/Shop.gd

scripts/game.gd

scripts/ui/display_piece_manager.gd