Put sidebar contents inside a scroll view

That means that you can't depend on the parent height and such any more. Luckily I already changed that in the previous commit.

Contributes to issue CURA-4148.

resources/qml/SidebarSimple.qml

@@ -25,6 +25,16 @@ Item
     Component.onDestruction: PrintInformation.enabled = false
     UM.I18nCatalog { id: catalog; name: "cura" }
 
+    ScrollView
+    {
+        anchors.fill: parent
+        style: UM.Theme.styles.scrollview
+        flickableItem.flickableDirection: Flickable.VerticalFlick
+
+        Rectangle
+        {
+            width: childrenRect.width
+            height: childrenRect.height
             Item
             {
                 id: infillCellLeft
@@ -471,19 +481,6 @@ Item
                 onModelChanged: populateExtruderModel()
             }
 
-    function populateExtruderModel()
-    {
-        extruderModel.clear();
-        for(var extruderNumber = 0; extruderNumber < extruders.rowCount() ; extruderNumber++)
-        {
-            extruderModel.append({
-                text: extruders.getItem(extruderNumber).name,
-                color: extruders.getItem(extruderNumber).color
-            })
-        }
-        supportExtruderCombobox.updateCurrentColor();
-    }
-
             Item
             {
                 id: tipsCell
@@ -604,3 +601,18 @@ Item
                 storeIndex: 0
             }
         }
+    }
+
+    function populateExtruderModel()
+    {
+        extruderModel.clear();
+        for(var extruderNumber = 0; extruderNumber < extruders.rowCount() ; extruderNumber++)
+        {
+            extruderModel.append({
+                text: extruders.getItem(extruderNumber).name,
+                color: extruders.getItem(extruderNumber).color
+            })
+        }
+        supportExtruderCombobox.updateCurrentColor();
+    }
+}