replace fontrenderer.h include with forward declaration

in order to flatten the build dependency tree further, include
fontrenderer.h directly where needed, in header files a forward
declaration is enough

src/gui/widget/progresswindow.cpp

@@ -32,6 +32,7 @@
 #include <global.h>
 #include <neutrino.h>
 
+#include <driver/fontrenderer.h>
 #include <driver/display.h>
 
 CProgressWindow::CProgressWindow(CComponentsForm *parent)