[Gretl-devel] filters: functions and GUI

In response to comments from Ignacio and Patricio I have now enhanced the functions movavg, hpfilt and bkfilt so that it's easier to do via the command-line what you can do via the GUI filter dialogs (please see the updated function reference for details). And if you save filtered series via the GUI that is now recorded in the command log. Allin.