0.6.1

Fixed

• The simulator let a discrete write of zero land on an enum. Hardware
  never does: sub 09 carrying a zero value IS the zeroed GET, and it reads
  rather than writes for EVERY parameter, not only the continuous ones. The
  proof was already in device.set_param_ordinal, which sends ordinal 0 as a
  CONTINUOUS 0.0 precisely because the discrete path cannot carry it.
• 0.6.0 shipped the narrower guard, taken from #37 while merging #35 on the
  reasoning that it protected a legitimate discrete write of ordinal 0. There
  is no such write. Narrowing by parameter kind invented a distinction the
  device does not make, and left the simulator MORE permissive than the
  hardware, which is the wrong direction for a test double: code doing a
  discrete zero would have passed here and silently done nothing on the rig.
  Reported by @bschmalz81401 on #37.
• test_zeroed_get_is_noop now stands the settle window down. It had been
  passing for a reason unrelated to what it claimed: the window served the
  read from the pre-write snapshot while the live buffer had already been
  zeroed, so the damage was hidden on any machine fast enough. It failed only
  on CI. With no window there is nowhere for a bad write to hide, and a
  companion test now covers the enum case the old guard got wrong.