Fix "Hide Boids on Title Screen" Setting to use alpha-based tweens

[Xevion]

I was able to get Tweens to modify the BoidController's alpha successfully and LeanTween was able to modify it properly, but the lowest available opacity seemed to only remove color from the Boid objects - they turned gray, two shades darker than the background.

Why this is occurring is still a mystery to me, but I should try testing new materials or shaders (perhaps a fix could be discovered while developing custom shaders later on) in order to fix this properly. The only other culprit would be the light, but it's probably not casting shadows as the light's shadow option is turned off.