STEEM-CRT

This is just a slightly modified version of the standard SteemSSE Atari ST emulator. I have just hacked in my own shader which emulates some aspects of old CRT monitors, as I prefer to play emulated games with such a filter, and the built-in SteemSSE scanlines are not to my taste. I made this because I wanted it myself, but since I have it I thought I'd share it. There's probably lots of things wh…