[LyX/master] Remove superfluous class definitions.

[Stephan Witt]

commit 3218d32ace5e8c74a0ddd3790c79c2396189707d
Author: Stephan Witt <sw...@lyx.org>
Date:   Sun Aug 24 20:32:01 2014 +0200

    Remove superfluous class definitions.

diff --git a/src/frontends/qt4/GuiApplication.h 
b/src/frontends/qt4/GuiApplication.h
index 3d5b2d2..79da314 100644
--- a/src/frontends/qt4/GuiApplication.h
+++ b/src/frontends/qt4/GuiApplication.h
@@ -19,10 +19,6 @@
 #include <QList>
 
 class QAbstractItemModel;
-class QIcon;
-class QObject;
-class QSessionManager;
-class QSortFilterProxyModel;
 
 namespace lyx {