midipix.sh:
    - Detect if ${MIDIPIX_PATH}/native/lib contains shared objects that
      are symbolic links and offer to convert them to hard links. As this
      has been a problem numerous times before, midipix.sh now explicitly
      handles this.
    - Launch mintty w/ the ntctty default of 80 rows and 120 columns.
    - Only handle Cygwin pathnames, be they absolute or relative.
    - Print the ntctty PID 0.25 seconds after launching it and optionally
      tail(1) -f ${MIDIPIX_PATH}/native/bin/libpsxscl.log if -l was specified,
      both to aid debugging.
    - Sanity-check ${MIDIPIX_PATH}/native/bin for required binaries.
    - Simplify the Midipix shell invocation command sequence; ${PATH} is
      now initialised to `/bin:/lib' only, absolute pathnames are only
      used for ${MIDIPIX_PATH}/native/lib in order to launch ntctty.