This duplicated feature existed because of bootstrapping issues
with LIT", but again, with careful threading, we can clean things
up.
We can now have a proper "Collapse OS" prompt :)
I'm not sure why I chose null-terminated initially. Probably because
the z80asm version had null-terminated strings.
Length-prefixes strings are the traditional form of strings in Forth
and it's a bit easier to work with them with traditional forth words
when they're under this form.
