Mark two new strings for translation.

Those strings weren't marked for extraction but we were trying to retrieve
their translation later.

At the same time, change the strings lookup context...

mythplugins/mythgallery/mythgallery/imageview.cpp

@@ -110,13 +110,13 @@ ImageView::ImageView(const ThumbList &itemList,
     if (slideShow > 1)
     {
         m_slideshow_sequence = new SequenceShuffle(m_itemList.size());
-        m_slideshow_mode = "Random Slideshow";
+        m_slideshow_mode = QT_TR_NOOP("Random Slideshow");
         m_pos = 0;
     }
     else
     {
         m_slideshow_sequence = new SequenceInc(m_itemList.size());
-        m_slideshow_mode = "Slideshow";
+        m_slideshow_mode = QT_TR_NOOP("Slideshow");
     }
 
     m_pos = m_slideshow_sequence->index(m_pos);
@@ -175,7 +175,7 @@ void ImageView::UpdateLCD(const ThumbItem *item)
 QString ImageView::GetDescriptionStatus(void) const
 {
     if (m_slideshow_running)
-        return " [" + QObject::tr(m_slideshow_mode) + "]";
+        return " [" + tr(m_slideshow_mode) + "]";
 
     return "";
 }

mythplugins/mythgallery/mythgallery/imageview.h

@@ -34,6 +34,8 @@ class ThumbItem;
 
 class ImageView
 {
+     Q_DECLARE_TR_FUNCTIONS(ImageView)
+
   public:
     ImageView(const ThumbList &itemList,
               int *pos, int slideShow, int sortorder);