[gnome-calculator] Added pi button to programming mode (fixes #153)

[Robert Roth <robertroth src gnome org>]

commit 788cbb54db4f66422927a70908ee1baac75c1677
Author: Robert Roth <robert roth off gmail com>
Date:   Thu Jun 4 16:11:25 2020 +0300

    Added pi button to programming mode (fixes #153)

 src/buttons-programming.ui | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
---
diff --git a/src/buttons-programming.ui b/src/buttons-programming.ui
index f8e33b62..5178ed62 100644
--- a/src/buttons-programming.ui
+++ b/src/buttons-programming.ui
@@ -1334,6 +1334,29 @@
             <property name="top_attach">1</property>
           </packing>
         </child>
+        <child>
+          <object class="GtkButton" id="calc_pi_button">
+            <property name="visible">True</property>
+            <property name="can_focus">True</property>
+            <property name="receives_default">True</property>
+            <property name="use_underline">True</property>
+            <property name="focus_on_click">False</property>
+            <property name="tooltip_text" translatable="yes">Pi [Ctrl+P]</property>
+            <property name="action_name">cal.insert-general</property>
+            <property name="action_target">'π'</property>
+            <child>
+              <object class="GtkLabel" id="pi_label">
+                <property name="visible">True</property>
+                <property name="label">π</property>
+                <property name="use_markup">True</property>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="left_attach">9</property>
+            <property name="top_attach">1</property>
+          </packing>
+        </child>
         <child>
           <object class="GtkButton" id="calc_integer_portion_button">
             <property name="label">int</property>