[Gretl-devel] "set plot_collection" doc

I realised that one of the new features was not documented in the xml file, so I added a paragraph. If someone could take a look to what's in git, that'd be great. ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti -------------------------------------------------------