- fixed: routine int21ah9 did use DOS, even if InDos flag was set.
   - fixed: reading stdin from file wasn't fully MS Debug compatible.
   - fixed: correctly handle tabs if output is via BIOS.
   - fixed L/W cmds: error msg for read/write drive was crumbled since
     v1.18.
   - ensured the correct video page is used when debugger has to display
     something if the InDOS flag is set AND page swapping is active.
   - mktables.c fix: didn't generate a valid debugtbl.inc.
   - added a "boot" variant of the debugger - DebugB.bin.
   - added a ring0 (PL0) variant of the debugger - DebugR.bin.
   - DI cmd may be activated for standard DEBUG.COM.
   - DEBUGX fix: restore hooked protected-mode interrupts when client
     terminates.
   - DEBUGX fix: c & s cmds finally work with 32-bit offsets.
   - DEBUGX fix, e cmd: generate a GPF if no data alias can be found for
     a code segment ( instead of silently skip the write ).
   - DEBUGX fix: disassembly of [CS:IP] in register dump may have caused
     a GPF in debugger if the memory address was beyond seg limit - 3.
   - DEBUGX fix, g cmd: if multiple breakpoints with different segment
     parts were set in protected-mode, hazardous writes may have happened.
   - DEBUGX fix, m cmd: '$' qualifier for the source address segment was
     rejected.
   - DEBUGX fix, c & m cmds: if both source and destination segment parts
     were readonly, the scratch selector was used twice.
   - DEBUGX: added cmdline option /2.
   - DEBUGX: hook into protected-mode debug interface Int 41h and make
     debugger visible there.
   - DEBUGX, a & e cmd: usage of scratch descriptor for readonly segments
     now hidden, so the displayed address' segment part isn't changed.
   - DEBUGX, a & d cmd: default segments are no longer automatically
     converted to selectors during initial switch to protected-mode.
   - DEBUGX: exceptions 0dh/0eh are set/reset on debugger entry/exit.
   - DEBUGXV: stop in debugger if SYSREQ is pressed.