Some additional features and fixes that either didn't make it into Update #3 or I only figured out with help from players after the fact.

CHANGES:

• Added an option in DISPLAY to change the texture of billboard particles (default SQUARE)
  • Choices include CIRCLE, HEX, STAR and CLOUD
• Non-glow particles will now be tinted according to the ambient light.
  • They will also be shaded depending on the camera's angle relative to light direction

FIXES

• Game will no longer break if the custom model directory doesn't exist or is inaccessible
• Double burst/dash bug fixed
• Tentatively fixed ground boost speed bug
  • It shouldn't throw you around as fast
• Buildings shouldn't trigger the HIT and DESTROY alerts