Waifu2x integration

[ZenoArrows]

Given how low resolution most ONScripter games are I've implemented Windows support for Waifu2x as a scaling algorithm instead of simply using linear upscaling (with linear upscaling as a fallback if Waifu2x is unavailable). Would you be interested in a pull request with this feature? It supports both on-the-fly upscaling using the original assets or offline upscaling using the conversion tools.