New tutorial stage

Added tutorial scene - Added a tutorial handler script for logic handling - Updated the game flow logic to account for a tutorial - Added new materials, music, and scripts for the tutorial - Added new intro - Updated the players' death explosion sound - Updated the players' animator state machine a bit - Updated the footsteps sound to match feet on the ground for the player - Fixed the player showing up alongside its explosion - Improved the Pixel Emitter script to match better the scene lighting - Updated the defeated player shader to use additive instead of color for the color mode. Also made the base color black - Changed the default volumes to maximum now that the audio clips were updated