Use PascalCase for Qt client filenames

Split FileTree.{h,cc} and FilterBar.{h,cc} files so that each class
is in its own file.

This breaks translations (some classes got renamed => context changed),
to be fixed by next commit (along with Tx sync).

qt/TrackerModelFilter.h

@@ -0,0 +1,33 @@
+/*
+ * This file Copyright (C) 2010-2015 Mnemosyne LLC
+ *
+ * It may be used under the GNU GPL versions 2 or 3
+ * or any future license endorsed by Mnemosyne LLC.
+ *
+ * $Id$
+ */
+
+#ifndef QTR_TRACKER_MODEL_FILTER_H
+#define QTR_TRACKER_MODEL_FILTER_H
+
+#include <QSortFilterProxyModel>
+
+class TrackerModelFilter : public QSortFilterProxyModel
+{
+    Q_OBJECT
+
+  public:
+    TrackerModelFilter (QObject *parent = 0);
+
+  public:
+    void setShowBackupTrackers (bool);
+    bool showBackupTrackers () const { return myShowBackups; }
+
+  protected:
+    bool filterAcceptsRow (int sourceRow, const QModelIndex&sourceParent) const;
+
+  private:
+    bool myShowBackups;
+};
+
+#endif // QTR_TRACKER_MODEL_FILTER_H