Tetrix v2.0 Is Here!

Tetrix v2.0 is finally here! This update is the biggest yet, with new 60fps gameplay, Hold, and more!

Full list of additions:
- Game now runs at 60fps
- DAS adjusted for new framerate
- Hold mechanic added
- All existing themes updated to support Hold piece display
- New "Galaxy" theme, including unique sound effects
- Completely new Main Menu screen
- New Settings screen
- Minor bug fixes
- Scoring adjustments