9.4 changes:
- updated version to 9.4
    bintar README NOTICE makefiles/Mf-install.in scheme.1.in
    c/Makefile.i3nt c/Makefile.a6nt c/Makefile.ti3nt c/Makefile.ta6nt
    mats/bldnt.bat workarea c/scheme.rc s/7.ss s/cmacros.ss
    release_notes/release_notes.stex csug/csug.stex
- added missing include
    killme.c
- added new mat verifying that primitives raise exceptions for invalid
  arguments based on primdata.ss signatures.  fixed some of those
  signatures, which weren't otherwise used except for arity checking.
  fixed some issues turned up by the test with who reports errors
  and how.
    primdata.ss, 5_1.ss, 7.ss, compile.ss, cpnanopass.ss, fasl.ss,
    interpret.ss, io.ss, record.ss, syntax.ss,
    primvars.ms, 5_1.ms, 7.ms, 8.ms, record.ms, mats/Mf-base,
    root-experr*, patch*
- string comparisons (string=?, string-ci<?, etc.) now get out fast
  when handed eq arguments.
    5_4.ss
- changed representation of most-negative iptr, I32, and I64 to make
  Visual C compiler happy.  updated windows make files, which had
  fallen out of date.  added missing hsrc= files sort.h and thread.h
  so they show up in the Windows workarea c directory.
    cmacros.ss,
    fasl.c, number.c, c/Mf-base, c/Makefile.{t,}{i3,a6}nt
- The scheme.h definition of Sfixnum(x) now uses multiply rather than
  left shift to avoid counting on the behavior of << on negative numbers,
  which is undefined in C.
    mkheader.ss
- Fixed a couple of casts, one harmless and the other causing
  Sinteger64_value to return 0 for the most-negative I64 on 32-bit
  builds.
    number.c
- The configure-generated Makefile distclean target no longer removes
  zlib and nanopass, since they are logically part of the git clone.
  It does run make distclean in zlib.
    makefiles/Makefile.in
- converted s_test_schlib shifts of -1 to equivalent shifts of 1 to
  avoid undefined left-shift behavior on negative numbers.
    prim5.c
- added if(---) {} wrapper around call to WRITE in display macro to
  silence unused return-value warnings.
    prim5.c
- liberalized get-mode check for ../mats.  it's not our business whether
  people make their directories group and/or other writeable.
    6.ms
- fixed time-utc->date test in mat time&date-printing to work regardless of
  what locale (and time zone) the host machine has set.
    date.ms
- added custom install options.
    configure newrelease scheme.c heappath.h.in