Support the (transfer) annotation for properties.

* girepository/*: Add g_property_info_get_ownership_transfer() and write
  the transfer attribute of properties into the typelib.

* giscanner/*: Parse the (transfer) annotation and write it into the .gir.

* tools/generate.c: Read the transfer annotation for properties and write
  to the .tgir.

https://bugzilla.gnome.org/show_bug.cgi?id=620484

gipropertyinfo.h

@@ -35,6 +35,7 @@ G_BEGIN_DECLS
 
 GParamFlags  g_property_info_get_flags (GIPropertyInfo *info);
 GITypeInfo * g_property_info_get_type  (GIPropertyInfo *info);
+GITransfer   g_property_info_get_ownership_transfer (GIPropertyInfo *info);
 
 G_END_DECLS