Improve Gio::Socket documentation.

* gio/src/socket.hg: Added documentation for the bind(),
  listen() and accept() methods, based on original Glib
  API reference but mentioning our exceptions rather than
  GError or return values.
  Bug #725178
Gio::Socket docs: Do not say that the Cancellable (reference) can be 0.

* gio/src/socket.hg: That makes sense only in the C API, which uses
  a pointer. We instead have method overloads without that parameter.
Gio::Socket::bind() docs: Use @a instead of <tt></tt> for a parameter.

* gio/src/socket.hg: @a is the doxygen way to say that we are
  referring to a parameter in the method being documented.
Regenerated methods .defs
Regenerated signal/property .defs
Regenerated docs XML
Fix tiny typo in commit
Regenerate docs XML.
2.39.91
win32: Surround content_type_get_symbolic_icon() with ifdefs.

This matches a similar ifdeffing in the underlying C header,
because ths function is apparently not useful on win32.
Add ActionMap to gio_extra_objects.defs.

This lets the documentation generator guess the appropriate C++ method
name.
Application: Add add_main_option_entry() and add_option_group().

* gio/src/application.hg: Wrap g_application_add_main_option_entries()
  and g_application_add_option_group().
Glib::ustring docs: Say more clearly that it must be only UTF-8

* glib/glibmm/ustring.h: Mention in the documentation of ustring and
ustring_Iterator that bad things can happen if the string does not contain
only valid UTF-8 data. Bug #681560.
Merge branch 'master' of git://git.gnome.org/glibmm
JOHNE - Bump the version number to 2.39.91