Switch to side-by-side view

--- a/GUI/playlist/view/ContextMenu.cpp
+++ b/GUI/playlist/view/ContextMenu.cpp
@@ -40,6 +40,7 @@
     _append_action = new QAction(QIcon(Helper::getIconPath("append.png")),
                                  tr("Append"), this);
     _sort_tno_action = new QAction(tr("Sort by track number"), this);
+    _invert_selection_action = new QAction(tr("Invert Selection"), this);
 }
 
 
@@ -63,6 +64,8 @@
                SIGNAL(sig_play_next_clicked()));
     disconnect(_sort_tno_action, SIGNAL(triggered()), this,
                SIGNAL(sig_sort_tno_clicked()));
+    disconnect(_invert_selection_action, SIGNAL(triggered()), this,
+               SIGNAL(sig_invert_selection_clicked()));
 }
 
 void ContextMenu::setup_entries(int entries)
@@ -104,4 +107,9 @@
         connect(_sort_tno_action, SIGNAL(triggered()),
                 this, SIGNAL(sig_sort_tno_clicked()));
     }
+    if (entries & ENTRY_INVERT_SELECTION) {
+        this->addAction(_invert_selection_action);
+        connect(_invert_selection_action, SIGNAL(triggered()),
+                this, SIGNAL(sig_invert_selection_clicked()));
+    }
 }