This implements the principle of "least surprise", in that users won't
normally expect to start overwriting an existing file on these devices.
Real hardware didn't behave that way. A new (empty) file can always
be created with the -N switch on the ATTACH.
Added BASE option to auxcpu to move memory region.
Fix errors in Card Reader/Card Punch translation and operation.
Fixed problems with ITS quantum timer.
Added support for System Concepts DC10 disk controller (Lars).
Fixed errors in Line Printer control codes.
Added support for Lines per page to LP10.
Fixed issues with 7 track tapes on TM10.
Updated user guides
