Update to 2.20.1:

2.20.1 (stable):

Glib:
* Date: Constructor: Check for invalid dates.
  (Jos辿 Alburquerque)
* ustring: Make the relational operators work with mixed argument types.
  (Chris Vine) Bug #580773

* Allow dynamic GType registration, though this is not yet fully tested:
Class: Added a register_derived_type(GTypeModule*) overload to
call g_type_module_register_type() instead of g_type_register_static().
gmmproc: Added a _DYNAMIC_GTYPE_REGISTRATION() macro to
be used in the class in the hg file, to add a *_Class::init(GTypeModule)
method, and a get_type(GTypeModule*) method that calls it.

Gio:
* File: Added the missing make_directory_with_parents() definition.
  (Siavash Safi)

Build:
* Fix the build with exceptions disabled.
  (Daniel Elstner, Jos辿 Alburquerque)
* Fix compiler warnings.
  (Daniel Elstner, Hubert Figuiere)
* Windows build fixes.
  (Armin Burgmeier)

Documentation:
* Improve the guessing of C++ method names for C function names.
  (Johannes Schmid)

(wiz)