* Move initial batch of shaders and presets to smoothing subdirectory
* Rename smoothing to edge enhancement
* Move cubic and windowed into interpolation
* Fix some presets
* Fix rest of presets
* Rename edge-enhancement to edge-smoothing
* Move pixel art scalers into separate directory separate from 'interpolation'
* Flatten interpolation/cubic into interpolation/
- New implementation of Film Grain that doesn't suck, so we can turn it up a nod by default. Supports RGB noise and shaping the distribution curve to control noise modulation. The previous implementation was just a placeholder, it was very basic.
- Greatly increased Anti-Aliasing quality in default preset.
- Include license headers to make clear that all my contributions are released on the public domain under the terms of the Unlicense. Anyone can do whatever they want with this.