Loadable ROMs

I added some items to the menu and some of it even works. You can now load ROM sets; I added a few in the zip file.
For a true 2001 experience, turn the screen white-ish, enable screen blanking on EOI, load the 2001 character set (different in lower case mode!) and the 2001 ROMs. Too bad you can't reduce the memory size to 8 KB yet...