ghost Class

• extends the moving entity class
• setup the scared state and associated sprites : in this state, the sprites are common for all ghosts (might be better to use a shared single init of a sprite vector)
• init with the correct sprites for each ghost
• pathfinding
• direction reverse
• fix display over pellets
• fix death & collisions
• check superpower duration
• fix start ghost
• rework animate()
• special cells (tunnel, house) & cornering for pacman
• upgrade chase mode
• ghosts common status handle
• ghost own counter & leave house
• ghost house vertical movements
• ghost house global timer
• ghosts reset (life lost, game over, level up)
• house