* DebugR fix: debugger assumed a 32-bit ring0 SS register on init;
  if this wasn't true, a crash may have occured.

* fix r cmd: the disassembler tried to show memory contents for the LEA
  instruction - this may have caused a GPF.

* DebugX fix e cmd, prompt mode: segment part changed to scratch sel
  after first line in protected-mode if it was a r/o selector.

* fix e cmd, prompt mode: '-' after byte input did skip that input.

* fix u cmd: address size prefix 67h for string instructions.

* fix n cmd: names > 128 chars may have modified debug's code seg.

* fix l & q cmd: failure of debuggee termination was ignored and the
  command continued, leaving an orphaned debuggee in memory.

* fix a cmd: regression since v1.18: "call/jmp [mem_ref]" without a size
  given did default to a far call/jmp.

* fix u cmd: operand size prefix 66h for 8/16/32-bit relative jmps.

* fix a cmd: NEar qualifier was accepted/ignored for immediate far
  jmp/call.

* u cmd, call far [mem]: qualifiers "FAR"/"DWORD FAR" changed to
  "FAR16"/"FAR32".

* DebugR(L): Q cmd may be activated for this variant.

* cmds bp/bc accept up to 4 permanent breakpoints.

* cmds bp/bc implemented, but inactive for Debug & DebugX; activated in
  DebugXg & DebugXv variants.

* G/T/P cmds: if possible, 386 debug registers will be used to set
  temporary breakpoints. Active for DebugX, DebugR(L).

* new cmdline options /s and /v for debugger variants that may use
  hardware breakpoints ( option /v not for DebugR(L) variant ).

* g cmd: if a breakpoint cannot be written, the cmd is aborted.

* Debug & DebugX may now be created in .exe file format.

* mktables.c: creates ASMTBL.INC/DISTBL.INC instead of DEBUGTBL.INC.

* cmds a, u: instruction RDTSC added.

* another variant of DebugR - DebugRV, with support for V86 mode.

* DebugR(V) dt cmd: optionally displays trapped ports.

* DebugRV di cmd: displays IDT & IVT vectors.

* DebugR rn cmd: won't run cmd if CR0.EM is set.