0.1.3: Menu and Flow improvements

Reworked menus:

• Added menu intro scene, with menu overlayed on trail.
• Fixed background blend, making menus easier to read.
• Added navigation sounds.
• Moved some sounds to menu entry and selection changes.

Bug Fixes:

• Fixed random seeding on startup, resulting in randomised levels/walls again.
• Fixed pause menu unfreezing time.

Leaderboards:

• Started making some changes to allow the display of top 3 target scores while in-level.

Known Issues:

• Minimizing the game, or losing focus, can result in menu with time unfrozen.