The new background now briefly fades in. The reason we didn't do this to
date is that there could be a perceived decrease in brightness as the old
and new background transition through opacity.
But a quick fade in, it doesn't seem to cause any visual artifacting.
I've also added a scale effect because it felt quite nice. Willing to
pull that if anyone has an issue with it, but it's a step in the
direction of "adding more motion to song select", which is still an area
I see lacking greatly – even compared to stable.
To avoid further floating-point comparison bugs, remove all usages of
Bindable<{float,double}>, replacing them with their
Bindable<Float,Double> counterparts.