POV-Ray [plugin] (updated: 2016/Aug/08)

[micheus]

If you have to add something during the export for Pov-Ray, that is how it works for YafaRay. On export -a is added to the command line...

Yes. It can be done by using +UA in the command line, but I will prefer to add an option to the Options dialog since it will require a change to the background property in the exported file.
Currently (for a gray color) that information is written to the exported file like this:
background { rgb <0.160784, 0.160784, 0.160784> }
and in order to the command line works we will need to adjust it to:
background { rgbt <0.160784, 0.160784, 0.160784, 1.0> }