This will make it easier to fit BR* in there.

Still binary matching. Next step is branching support.

So far, the resulting binary matches.

This allows us to remove a lot of labels usage in boot code. This
commit has no effect on forth.bin.

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

More portable

It was ill-advised.

I hadn't noticed that this word was almost ANS compliant.

Instead of letting each configuration taking care of RDLN$ and
"CollapseOS" prompt, move this to BOOT to simplify xcomp units.

Initialization source code is now only for driver initialization.

Previously, calling quit would break EOT behavior and not properly
quit Collapse OS.

Verifying that forth.bin is stable is enough. Also, fix shebang.

During "make updatebootstrap", we use less than 0x20 bytes on the
PSP side and less than 0x40 bytes on the RSP one. 0x100 bytes ought
to be enough for anybody.

Use straight VARIABLE instead of Z80MEM+. Initially, I used this
system to allow z80a to be embedded in a system binary, but now
I don't think it's worth it. Compiled, z80a is 2.5k. Sure, it's a
sizeable amount of RAM, but I think that even with it in RAM, I'll
manage a bootstrap within my most constrained machine, the SMS with
8K.

Not worth the trouble. Easier to set jump in binary directly.

It's now much easier...

Finally got rid of the XPACKed core and managed to cross-compile
all core words, which greatly simplifies the bootstrapping process.

Saves us an (ok) indirection and will save us more soon.