Adding additional export options when exporting polefigure

This is a user request. I still need to discuss this with Weimin, but this fullfill already his request. I put the MR here to make you aware that I'm almost done with this change

This change allows to add more option to export dialogs. In MR 138 Weiming requested to add these additional export functions to give them more freedom when saving their work. Apparently in earlier version of Steca this options was available ( < 2019 ).

Resolves #138 (closed) #74 (closed)