Add LMP88959's "NTSC-CRT" filter

[vadosnaprimer]

https://github.com/LMP88959/NTSC-CRT

NTSC encoding/decoding in C89 using only integers and fixed point math. Can be used as an image filter for games or real-time applications.

MAME and RetroArch have CRT shaders of all sorts, so if we want to attract their users, we would greatly benefit from this filter, both in real time play and in video recordings.