[gnome-calculator] Added Ctrl+O shortcut for degree symbol

[Robert Roth <robertroth src gnome org>]

commit 47cf4566da45f9103394808653f222bcb76f614a
Author: Robert Roth <robert roth off gmail com>
Date:   Mon Mar 8 10:54:58 2021 +0200

    Added Ctrl+O shortcut for degree symbol

 src/math-display.vala | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/math-display.vala b/src/math-display.vala
index d810b260..8ecd7bdb 100644
--- a/src/math-display.vala
+++ b/src/math-display.vala
@@ -322,6 +322,9 @@ public class MathDisplay : Gtk.Viewport
             case Gdk.Key.r:
                 equation.insert ("√");
                 return true;
+            case Gdk.Key.o:
+                equation.insert("˚");
+                return true;
             case Gdk.Key.u:
                 equation.insert ("µ");
                 return true;