And adjust rc2014/eeprom recipe

XPACK is more efficient than stripfc was, we can pack more stuff in 8K.
We now have enough space to fit readln.

As long as our target was the first word of the "user" dict, using
target's prev to compute offset was fine, but when the target is not
the first word, this system breaks down.

This is the case when, instead of including source code in our boot
binary, we paste it in Collapse OS' prompt.

Also, adjust RC2014 recipe to include stage 3 assembling instructions
with the "paste into prompt" method.

It makes the tool much more versatile. I'll have adev being included
in all recipes, so it can be assumed.

The former was only used in the peculiar context of "/emul". The
regular case is actually HERE pointing to RAMEND on boot.

This allows us to get rid of the zasm.sh wrapper.

fixes #80

Drop the "{pre,post}-collapse" thing and specify that the rc2014 recipes
are canonical.

This allows us to write to an AT28 EEPROM from within collapse os.

Also, remove `parts/platforms`. It makes no sense. Only recipes make
sense.

This introduces `core.asm` which includes routines used by other parts.

Also, come up with a way to make parts play well together memory-wise.