gnuplot release 6.0.4 tarball

[Ethan A M. <me...@uw...>]

I have created a release directory on SourceForge for version 6.0.4

   https://sourceforge.net/projects/gnuplot/files/gnuplot/6.0.4/

The directory is "staged" for three days, which means only the developer
group can access it.  On 19 December it will become publically accessible
and I will send out a release announcement.

The release package includes Bastian's updates to the various Windows
configuration directories and build script (added since the testing versions),
and two final bug fixes.

The tarball content matches the state of git commit 3726262627

cheers,
        Ethan