EOF while reading, use Idle callback to consume some CPU time and keep
the emulation going. This fixes a known issue where 'CTTY NUL', changing
the console to NUL, causes DOSBox-X to hang and become unresponsive.
While the shell itself is hung still, the emulation continues and the
user can safely exit or restart the emulator without having to use their
OS's facilities to force DOSBox-X to exit. Removed debug messages from
NUL device.
being thrown. DOS_Shell given a destructor so it can free the batch file
object on shutdown. Both fix about 4-5 reported memory leaks reported by
Valgrind.
INT 2Fh at the head of the call chain. This way, the DOS kernel can see
the Windows init broadcast at the bottom of the chain (before anyone
modifies registers) and the hook can see the resulting chain just before
it's returned back to WIN.COM.
