Changing the canvas size does not affect the effect size or position.
This feature provides a constant-looking output and makes it easier to adjust effects.
BREAKING CHANGE: If you update to v4, you may be required to adjust your UIParticle.scale.
Instead of one CanvasRenderer with submeshes, render with multiple CanvasRenderers.
This feature allows the number of materials to be unlimited.
close#122, close#152, close#186