Release 5.2.1

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

I have uploaded a tarball gnuplot-5.2.1.tar.gz to the usual SourceForge 
distribution site.

   https://sourceforge.net/projects/gnuplot/files/gnuplot/5.2.1/ 

This is a bit early for an incremental release but I want to put it out now
for two reasons.  

A cluster of related regressions were reported for the 5.2.0 handling of
log-scaled  axis ranges and tic generation.  I consider this regression
to be serious and worth repairing sooner rather than later.

It is not clear when the cvs->git conversion process will settle down to
the point where I am comfortable preparing an incremental release
from the new git repository.  Rather than waiting for that, I would rather
package up 5.2.1 from a final cvs snapshot plus a couple of last-minute
fixes that I will maintain on the side until the git conversion completes.

The list of changes between 5.2.0 and 5.2.1 includes

* NEW set table separator {tab|comma|"char"} allows creation of csv files
* NEW hotkey for changing azimuth in 3D plots with mousing
* NEW splot ... with lines title at {beg|end}
* NEW Rework gstrptime() to handle relative time formats tH tM tS
* NEW command "set rgbmax <value>" controls interpretation of input RGB values
* FIX allow mixed use of in-key plot titles and manually placed titles
* FIX prevent runaway iterations of the form   plot for [i=start:*] ...
* FIX handle in-line range limits for linked or nonlinear axes
* FIX restore pre-5.2 interpretation of logscaled tic increment as a multiplier
* FIX logscale tic placement is closer to that of versions before 5.2.0
* FIX recheck inrange/outrange points after spline or bezier smoothing
* FIX autoscaling of plots with linked axes where data is plotted on x2 or y2
* FIX sampling on x2 if linked to x1;  e.g. plot sample [t=1:5:1] '+' axes x2y1
* FIX empty range on logscale y axis is handled by auto-extending the range

More information in the ChangeLog.

	happy gnuplotting,

		Ethan