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.
This would allow things like temporary giving control to the *CL
line on the TRS-80. For example... A very far fetched example. Not
at all the only *raison d'etre* of the layer...
This is done by adding a "C<* override" layer that is reset to 0 on
ABORT.
The problem was that when ABORT happened during a LOAD, we had a
resetted RSP and started from a clean INTERPRET, but LOAD didn't
have the opportunity to restore C<*, which caused it to continue
interpreting from the faulty BLK.
With a C<* override, we don't need to *restore* C<*, we just need to
clear the override.
This is more than cosmetic, it's also highly usable. The presence
or absence of the "ok" message allows us to know whether the command
aborted. Previously, the "> " prompt appeared when the system expected
a prompt in the INTERPRET context, whether the previous command aborted
or not.
Also, this allows us to get rid of that ugly FLAGS global variable.
