Make calendar pin persistent across sessions

Summary:
A user can "pin" the calendar so that it won't get closed on focus
change, but only when the clock is clicked again.

This persists across open/close operations, but currently doesn't
persist across Plasma restarts.

This patch loads the saved config value of the last pinned state.

Test Plan:
Opened calendar, set pin, closed it, reopened and it was still pinned
(which is the current state)
killed plasma, restarted plasma, was still pinned (new)

Reviewers: #plasma

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D8252

applets/digital-clock/package/contents/config/main.xml

@@ -65,5 +65,9 @@
       <label>A list of plugins where additional calendar event data can be sourced.</label>
       <default></default>
     </entry>
+    <entry name="pin" type="Bool">
+      <label>Whether the popup should remain open when another window is activated</label>
+      <default>false</default>
+    </entry>
   </group>
 </kcfg>

applets/digital-clock/package/contents/ui/CalendarView.qml

@@ -120,6 +120,12 @@ Item {
             }
         }
 
+        Binding {
+            target: plasmoid
+            property: "hideOnWindowDeactivate"
+            value: !plasmoid.configuration.pin
+        }
+
         PlasmaComponents.Label {
             id: dayLabel
             anchors.left: parent.left
@@ -347,6 +353,7 @@ Item {
         height: width
         checkable: true
         iconSource: "window-pin"
-        onCheckedChanged: plasmoid.hideOnWindowDeactivate = !checked
+        checked: plasmoid.configuration.pin
+        onCheckedChanged: plasmoid.configuration.pin = checked
     }
 }