docs: update links to developer.gnome.org

The URL layout has changed. Fix the links and comment out one paragraph where
the doc is gone.
Fixes #702135

docs/faq/developing.xml

@@ -192,8 +192,11 @@ be indented, header files may be indented manually for better readability
 (however, please use spaces for indenting, not tabs, even in header files).
         </para>
         <para>
+<!-- TODO(ensonic): link is dead, pending question on desktop-devel
 As for the code itself, the 
-<ulink url="http://developer.gnome.org/doc/guides/programming-guidelines/book1.html">GNOME coding guidelines</ulink> is a good read.
+<ulink url="http://developer.gnome.org/doc/guides/programming-guidelines/book1.html">GNOME
+coding guidelines</ulink> is a good read.
+-->
 Where possible, we try to adhere to the spirit of GObject and use similar
 coding idioms.
         </para>

docs/manual/basics-elements.xml

@@ -283,9 +283,9 @@ main (int   argc,
     <para>
       For more information about <classname>GObject</classname>
       properties we recommend you read the <ulink
-      url="http://developer.gnome.org/doc/API/2.0/gobject/index.html"
+      url="https://developer.gnome.org/gobject/stable/rn01.html"
       type="http">GObject manual</ulink> and an introduction to <ulink
-      url="http://developer.gnome.org/doc/API/2.0/gobject/pr01.html" type="http">
+      url="https://developer.gnome.org/gobject/stable/pt01.html" type="http">
 	The Glib Object system</ulink>.
     </para>
     <para>

docs/manual/basics-init.xml

@@ -115,7 +115,7 @@ main (int   argc,
     </example>
     <para>
       As shown in this fragment, you can use a <ulink
-      url="http://developer.gnome.org/doc/API/2.0/glib/glib-Commandline-option-parser.html"
+      url="http://developer.gnome.org/glib/stable/glib-Commandline-option-parser.html"
       type="http">GOption</ulink> table to define your application-specific
       command line options, and pass this table to the GLib initialization
       function along with the option group returned from the

docs/pwg/intro-preface.xml

@@ -112,7 +112,7 @@
       understanding of the C language.
       Since &GStreamer; adheres to the GObject programming model, this guide
       also assumes that you understand the basics of <ulink type="http"
-      url="http://developer.gnome.org/doc/API/2.0/gobject/index.html">GObject</ulink>
+      url="https://developer.gnome.org/gobject/stable/pt01.html">GObject</ulink>
       programming. 
       You may also want to have a look
       at Eric Harlow's book <emphasis>Developing Linux Applications with