Transform patterns can be created from multiple base features

The infrastructure/piping seems to have been in place for a long while.
Not tested for all variations of pattern transforms.
The major enabler was removing the `break`.
Some extra piping added to let the code at call-site decide if to select multiple features or not.

src/Mod/PartDesign/Gui/TaskFeaturePick.cpp

@@ -80,6 +80,7 @@ const QString TaskFeaturePick::getFeatureStatusString(const featureStatus st)
 
 TaskFeaturePick::TaskFeaturePick(std::vector<App::DocumentObject*>& objects,
                                  const std::vector<featureStatus>& status,
+                                 bool singleFeatureSelect,
                                  QWidget* parent)
   : TaskBox(Gui::BitmapFactory().pixmap("edit-select-box"),
             tr("Select feature"), true, parent)
@@ -100,6 +101,10 @@ TaskFeaturePick::TaskFeaturePick(std::vector<App::DocumentObject*>& objects,
     connect(ui->listWidget, SIGNAL(itemDoubleClicked(QListWidgetItem *)), this, SLOT(onDoubleClick(QListWidgetItem *)));
 
 
+    if (!singleFeatureSelect) {
+        ui->listWidget->setSelectionMode(QAbstractItemView::ExtendedSelection);
+    }
+
     enum { axisBit=0, planeBit = 1};
 
     // NOTE: generally there shouldn't be more then one origin
@@ -276,7 +281,6 @@ std::vector<App::DocumentObject*> TaskFeaturePick::buildFeatures()
                     result.push_back(obj);
                 }
 
-                break;
             }
 
             index++;
@@ -525,10 +529,11 @@ TaskDlgFeaturePick::TaskDlgFeaturePick( std::vector<App::DocumentObject*> &objec
                                         const std::vector<TaskFeaturePick::featureStatus> &status,
                                         boost::function<bool (std::vector<App::DocumentObject*>)> afunc,
                                         boost::function<void (std::vector<App::DocumentObject*>)> wfunc,
+                                        bool singleFeatureSelect,
                                         boost::function<void (void)> abortfunc /* = NULL */ )
     : TaskDialog(), accepted(false)
 {
-    pick  = new TaskFeaturePick(objects, status);
+    pick  = new TaskFeaturePick(objects, status, singleFeatureSelect);
     Content.push_back(pick);
 
     acceptFunction = afunc;