gnuplot: update to 6.0.1

[remkos]

Description

Simple update to upstream version 6.0.1.
Also took up the recommendation from @markemer to replace +x11 by +qt in the default_variants.

Closes https://trac.macports.org/ticket/70357

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 14.6.1 23G93 x86_64
Command Line Tools 15.3.0.0.1.1708646388

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL in commit message?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?

[macportsbot]

Notifying maintainers:
@mojca for port gnuplot.

[markemer]

Maybe we should make the defaults +qt +lua +pangocairo and remove x11 as the web page suggests - we could also add qt6 as a variant. From http://www.gnuplot.info/ReleaseNotes_6_0_1.html:

The 6.0 source code supports three primary cross-platform interactive modes in addition to several platform-specific modes.

Qt

The qt terminal supports interactive display with menu-driven output to png, svg or pdf. If either Qt6 or Qt5 is detected by the configure script, this will be the default terminal. It is now the fastest and most full-featured interactive terminal option.

To disable this terminal or force use of Qt5 even if Qt6 is present
    ./configure --with-qt=qt5
    ./configure --without-qt 
Cairo/pango/wxWidgets

This set of terminals includes pngcairo, pdfcairo, epscairo, and cairolatex for output to a file. The wxt terminal provides interactive display All of these will be built by default if the configuration script finds the required libcairo, libpango, libcairo, libwxgtk, and related support libraries

To disable these terminals:
    ./configure --without-cairo
    ./configure --with-cairo --disable-wxwidgets 
X11 (the "classic" interactive interface)

This used to be the preferred interactive interface, but the newer wxt and qt terminals offer nicer output and a wider range of features.

[remkos]

@markemer : I did take up your suggestion to replace +x11 by +qt in the default_variants, as that is indeed what the developers favour.
I did not add a +qt6 variant, as I have no experience with it.

[markemer]

@markemer : I did take up your suggestion to replace +x11 by +qt in the default_variants, as that is indeed what the developers favour.

I did not add a +qt6 variant, as I have no experience with it.

Cool. We can do that later. This'll work.