Fix Black BG in Camera Shaders

This release should fix issues with camera shaders showing black backgrounds when rendering Cancerspace materials.

Specifically, an appropriate alpha value should now be returned when alpha values less than 1 are present in the GrabPass texture.

SPS-I Support

This release updates Cancerspace to use Single Pass Stereo Instanced rendering, since VRChat will be requiring it sometime in the future. Also it should now fall back to being invisible when shaders aren't being shown.

Cancerfree option

This release adds an additional shader called Cancerfree.
It's the same as Cancerspace, but has less features and doesn't use a Grab Pass, so it's a lot lighter on performance.
It also uses the native blending functions of DirectX instead of simulating them, so the blending options are a bit more aggressive. See the Blending tab.

Have fun 🥳

Upside Down Bugfix

There's been a long-standing bug where the shader would cause the screen to be flipped upside down for only some people who were in desktop.
This should fix it, I hope.

Color Falloff

You can now control falloff with vertex colors. This includes color properties from particle systems. Have fun.

Fixed a bug with cubemap rotations

Had a typo in there (._.")

Particle System Settings

thx for reminding me, rero

There are now particle system settings for dealing with falloff distance and lifetime.
You'll need to use Custom Vertex Streams on your particle system, use this setup:

Major Code Rewrite with a couple bugfixes

Did a ton of code cleanup.

Some minor bugfixes:

• Things should no longer look shitty at high speeds (image scroll speeds, wave distortion speed, screen shake speed, etc.)
• Color burning now no longer cancels bloom.

Triplanar projection mode.

Misc/Projection Type/Triplanar is now an option.
Also a depth-enabling prefab is now bundled with the shader for those who don't know how to or are too lazy to set up their own. This is necessary for depth falloff and/or triplanar projection.

Minor bugfix

• Fixed an issue where distortion maps weren't scrolling when overlay boundary handling was set to "clamp".