[Simh] AT&T 3B2 Emulator

[Seth Morabito]

Hello everyone,

I'm pleased to announce that the 3B2/400 emulator is now part of the
main SIMH code base.

I'd like to express my many thanks to Mark Pizzolato for doing the
merge and spotting compatibility issues, and to Charles Anthony for
his help in getting many last-minute details polished up.

>From now on, please consider https://github.com/simh/simh the sole
repository. I'll continue to make changes in my own fork, but will
open pull requests whenever there's a change ready to be merged.

-Seth
-- 
Seth Morabito
web at loomcom.com