Add first version of a new sidebar, including project selector.

The project selector also allows to select targets.
However, this is not yet used, since the necessary
changes are still being stabilized.

Done-with: con

src/plugins/coreplugin/coreimpl.cpp

@@ -33,6 +33,8 @@
 #include <QtCore/QCoreApplication>
 #include <QtCore/QSettings>
 
+#include <QtGui/QStatusBar>
+
 namespace Core {
 namespace Internal {
 
@@ -179,6 +181,11 @@ QMainWindow *CoreImpl::mainWindow() const
     return m_mainwindow;
 }
 
+QStatusBar *CoreImpl::statusBar() const
+{
+    return m_mainwindow->statusBar();
+}
+
 // adds and removes additional active contexts, this context is appended to the
 // currently active contexts. call updateContext after changing
 void CoreImpl::addAdditionalContext(int context)