GNOME Calculator 3.11.3 Adds Custom Functions

GNOME Calculator 3.11.3 introduces new custom functions, adds support for factorials of positive decimal numbers, uses HeaderBar, and depends on the latest releases of Vala and GTK+. Moreover, GNOME Calculator 3.11.3 no longer uses stock icons, repairs various compilation warning, fixes the title in basic mode, repairs the newline text wrap bug, finally fixes the “Malformed expression” bug, and fixes some typos and AppData.