Historically this functionality was reimplemented within each
DEVICE simulator often with slightly different implementations
and inconsistencies. Solving this globally within SCP required
changes in many places, but should henceforth be reasonably
managed.
As discussed in #1034
- Fix protect fault for 2-word instructions so that background tasks do not
crash.
- Lay the ground work for supporting the enhanced instruction set.
- Fix disk layout bug (disks are no longer compatible with previous version).
- Add debugging support for displaying MSOS 5 system requests.
- Fix bugs found by Coverity.
- add internal help entries
- add descriptions to the register, modifier and debug tables.
- changed device CD name to CDD to avoid name conflict with the CD command
