Overview of changes in gnome-calculator 3.15.1
    * New : Colored buttons (Elita Lobo)
    * New : History view (Elita Lobo)
    * Update : Update to latest GtkSourceView API (Yosef Or Boczko, Evan Nemerson)
    * Update : Support upcoming Vala 0.27 (Rico Tzschichholz)
    * Update : Increase search provider timeout (Michael Catanzaro)