Release 5.2.4

[sfeam <sf...@us...>]

Release 5.2.4 source tarball is ready and can be downloaded from

    https://sourceforge.net/projects/gnuplot/files/gnuplot/5.2.4/gnuplot-5.2.4.tar.gz

This release contains
- a fix for a serious regression reported against 5.2.3 (spurious
  evaluation of logscale coordinates as UNDEFINED)
- re-implementation of the "refresh" command to correct regressions in
  5.2.0 through 5.2.3
- sanity checks for several invalid command sequences found by fuzzing
- several minor bug-fixes
- two recent minor changes back-ported from the development version

Yes it's only been a month since 5.2.3 but I think the regression
in plotting logscale axes is serious enough to warrant an immediate fix.
If you want to test before/after here is a simple trigger for the error:
    set log y
    plot [1:100] x**2, 1/0

Windows binaries will follow eventually.

	happy gnuplotting

		Ethan