World 1 Demo is... updated?

That's right! I updated this World 1 Demo! Here's what's new:

• Added infotext in 1-3
• Changed player and box position in 1-19
• Made 1-5 and 1-6 slightly easier
• Tweaked some things in 1-16 and 1-17
• Scrapped 1-6 and rearranged levels
• 1-19 is now a new level
• Now the button sound plays when the player hits a button
• Made it so that button sound doesn't play when button is pressed
• Fixed level song overlaps title song bug
• Finally made the UI work in the Demoend