removal of Win16 support

[Bastian M. <bma...@we...>]

Hello,

the last official release of gnuplot for Win16 (3.7.3) is now 7 years 
old. I think it's about time to remove support for this platform altogether.

Below you find the output of diffstat for a preliminary patch that does 
that.

  config/config.nt       |    5 -
  src/alloc.c            |   10 --
  src/alloc.h            |    2
  src/command.c          |   42 +++-------
  src/eval.c             |    4
  src/fit.c              |    4
  src/gpexecute.c        |    3
  src/plot.c             |    2
  src/syscfg.h           |    2
  src/win/wcommon.h      |   17 ----
  src/win/wgnuplib.c     |   29 -------
  src/win/wgnuplib.h     |   19 ----
  src/win/wgnuplot.mnu   |    3
  src/win/wgnuplot.rc    |    6 -
  src/win/wgraph.c       |  120 +++--------------------------
  src/win/winmain.c      |   69 +++--------------
  src/win/wmenu.c        |   81 ++++----------------
  src/win/wpause.c       |   33 --------
  src/win/wprinter.c     |  197 --------------------------------------
-----------
  src/win/wtext.c        |   85 +++------------------
  term/win.trm           |   13 ---
  22 files changed, 93 insertions(+), 652 deletions(-)


In addition several build files could be removed (src/win/wgnuplot.def, 
wgnuplib.def, config/makefile.msw). config/makefile.win also contains 
16bit portions.

Please let me know how we should proceed.

Bastian