Overview of changes in gnome-calculator 51.beta
    * Updated translations
    * Show exponent in the current base #536 (Lukáš Tyrychtr)
    * Update and remove some currencies !464 (Jake Dane)
    * Persist calculation history across sessions !469 (Eric Friedman)
    * Report the name entry as invalid on the a11y layer !471 (Lukáš Tyrychtr)
    * Keep rational arithmetic exact (using gmp) !470 (Bruno Gonçalves)
    * Fixed compile warnings !472 (Lukáš Tyrychtr)