Added scroll bar to per object panel

If there are too many per object settings a scrollbar is now displayed

CURA-2131

plugins/PerObjectSettingsTool/PerObjectSettingsPanel.qml

@@ -154,11 +154,17 @@ Item {
         Column
         {
             spacing: UM.Theme.getSize("default_lining").height
-
+            // This is to ensure that the panel is first increasing in size up to 200 and then shows a scrollbar.
-            Repeater
+            // It kinda looks ugly otherwise (big panel, no content on it)
+            height: contents.count * UM.Theme.getSize("section").height < 200 ? contents.count * UM.Theme.getSize("section").height : 200
+            ScrollView
+            {
+                height: parent.height
+                width: UM.Theme.getSize("setting").width
+                style: UM.Theme.styles.scrollview
+                ListView
                 {
                     id: contents
-                height: childrenRect.height;
 
                     model: UM.SettingDefinitionsModel
                     {
@@ -259,6 +265,7 @@ Item {
                     }
                 }
             }
+        }
 
         Button
         {