Implement #545

* Instance group can be selected when creating and copying instances
* Original group is pre-selected when copying
* Last used group is pre-selected when creating new instances

gui/dialogs/CopyInstanceDialog.ui

@@ -17,7 +17,7 @@
    <string>Copy Instance</string>
   </property>
   <property name="windowIcon">
-   <iconset resource="../../graphics.qrc">
+   <iconset>
     <normaloff>:/icons/toolbar/copy</normaloff>:/icons/toolbar/copy</iconset>
   </property>
   <property name="modal">
@@ -42,7 +42,7 @@
      <item>
       <widget class="QToolButton" name="iconButton">
        <property name="icon">
-        <iconset resource="../../graphics.qrc">
+        <iconset>
          <normaloff>:/icons/instances/infinity</normaloff>:/icons/instances/infinity</iconset>
        </property>
        <property name="iconSize">
@@ -82,6 +82,33 @@
      </property>
     </widget>
    </item>
+   <item>
+    <layout class="QGridLayout" name="gridLayout">
+     <item row="0" column="0">
+      <widget class="QLabel" name="labelVersion_3">
+       <property name="text">
+        <string>Group</string>
+       </property>
+       <property name="buddy">
+        <cstring>groupBox</cstring>
+       </property>
+      </widget>
+     </item>
+     <item row="0" column="1" colspan="2">
+      <widget class="QComboBox" name="groupBox">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+       <property name="editable">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
    <item>
     <widget class="QDialogButtonBox" name="buttonBox">
      <property name="orientation">