Request for testing gnuplot with Qt 5

[Mojca Miklavec]

Hi,

I would be grateful for some testing of the qt terminal on gnuplot
(when compiled with +qt5), both on < 10.9 where stdlibc++ is used as
well as with newer versions of OS X.

I'm experiencing occasional (not to well reproducible) problems and
crashes, but I'm not sure what causes it. (It could be some
incompatibility with stdlibc++ and libc++, but it could just as well
be some bad thread management in gnuplot.)

There's also a tiny confusion with std::isnan() and isnan(). I'm not
sure what's the proper use of those and some combinations of Qt 4 vs.
5 and compiler version cause compile errors. Suggestions welcome.

Thank you,
    Mojca