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've mistakenly broken it in previous commit.

This was becoming heavy to manage.

This is the first commit I do entirely in VE. It's a habit I'm planning
on taking as it helps a lot to find usability issues.

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.

and renamed it "Core words". Also, reworded the presentation.

This allows us to move words like ABORT" to xcomp-core, which is
I think the last roadblock before being able to unify all drivers
into a single xcomp layer.

The goal is to insert device drivers in between.

That makes it easier to write drivers that can be xcompiled.

This allows us to get rid of the (parse*) indirection.

The way is clear for complete stage1 bootstrapping on the RC2014
target!