SHADERGROUP([path])
Sets the active shader group to the shader matching path
Can be one of the following shaders:
"spider""outline""desaturate""wobble""scan_pincushion""ntsc""creeper""color_convolve""blur""bits""blobs2""flip""invert""notch""antialias""entity_outline""bumpy""sobel""art""blobs""fxaa""pencil""phosphor""deconverge""green"
You can also use "+" or "-" to toggle between shaders.
Returns the name of the selected shader.