* Add gizmo-crt shader
This shader tries to reproduce a CRT-like output without replicating mask or RGB patterns.
It has the following features:
- allows fractional scaling
- uses texture AA shader and subpixel scaling for evenly placed sharp pixels
- has a horizontal blur function which mimics bad signal quality of some systems (megadrive, psx)
- has a vertical blur function which mimics n64 vertical software blur
- adds some noise to mimic restless CRT colors
- has a curvator function
- looks good with resolutions <= 1080p
- has modest system requirements
https://forums.libretro.com/t/gizmo-crt-shader/41409https://github.com/gizmo98/gizmo-crt-shader
