- Add patch gnuplot-5.2.0-texi2info.patch as source to be able
to patch the resulting gnuplot.texi
- Modify patches
* gnuplot-4.4.0-x11ovf.dif
* gnuplot-4.6.0-demo.diff
* gnuplot-4.6.0-fonts.diff
* gnuplot-4.6.0.dif
* gnuplot-QtCore-PIC.dif
* gnuplot-wx3.diff

- Update to gnuplot 5.2.0
* NEW user-defined dashtypes in metapost terminal
* NEW datablock contents may be accessed as an indexed array of strings
* CHANGE allow explicit sample interval for u and v using pseudofile '++'
* CHANGE decouple cbrange from color components in "with rgbimage"
* FIX reconcile aspect ratio flags from "set view map" and "set view equal xy"
* FIX "set key fixed" should be ignored in the case of "set view map"
* FIX GPVAL_* variables were not being updated in "set table" mode
* FIX evaluation of nested iteration containing an empty range
* FIX bug in variant time_spec formats %tH %tM (undesired wrapping)
* NEW "plot with table" can handle string-valued output columns
* CHANGE add caca terminal documentation to the user manual
* CHANGE revised output of "test" command
* CHANGE use Mingw-w64 and MSVC popen rather than built-in "fake" popen
* FIX copy environmental variable GNUTERM to internal variable on entry
* FIX more consistent handling of plot 'with table'
* FIX incorrect, possibly empty, command string was saved for previous fit
* FIX ignore non-numeric values of potential dummy params used by "fit"
* FIX autoscaling during refresh of volatile data plots "with vectors"
* FIX terminal initialization must be done before executing ~/.gnuplot