The second parameter of gtk_widget_set_realized is of type gboolean
(gint). This is to ensure compatibility on alternative compilers and
platforms.

Updated documentation and sample to use the new function API

This update replaces depreciated Gtk1.x symbols with Gtk2.x symbols in
preparation for adding Gtk3 support. These edits aim to be fully
compatible with Gtk2.x, allowing backward compatibility.

The following symbols have been replaced in this commit:

Gtk symbols that have been moved to the Gdk library:
 - GtkType -> Gtype
 - GTK_CHECK_CAST -> G_TYPE_CHECK_INSTANCE_CAST
 - GTK_CHECK_TYPE -> G_TYPE_CHECK_INSTANCE_TYPE
 - gtk_signal_connect -> g_signal_connect
 - GTK_SIGNAL_FUNC -> G_CALLBACK
 - gtk_type_class -> g_type_class_peek
 - gtk_type_new-> g_object_new
 - GtkTypeInfo -> GtypeInfo (Not required for
   g_type_register_static_simple)
 - gtk_type_unique -> g_type_register_static_simple
 - gdk_draw_image_rgb -> replaced by gdk_cairo_source_pixbuf
   NB: This requires porting to use cairo contexts and GdkPixbufs.

The following gtk symbols are changed for their modern equivalent:
 - GTK_WIDGET_REALIZED -> gtk_widget_get_realized
 - GTK_OBJECT_FLAGS -> gtk_widget_set_realized

Symbols without replacement:
 - gtk_range_set_update_policy -> No replacement; as default policy is
   set to continuous we can delete this line.

findHomagraphy can return empty Mat in master branch

Currently, there are different default typedefs for Point_, Size_, and Rect_. This pull request at least makes sure that default typedefs exist for int, float and double variants of each of these types.

GSoC Python Tutorials

removed white spaces

removed blank lines at EOF

removed duplicate labels

This makes them visible from the python bindings