doc: enforce some sane page order.

doc/00-page-order.dox

@@ -0,0 +1,23 @@
+/* This is here just to order the pages in some reasonable way. */
+
+/**
+
+@page getting-started Getting started
+@page features Feature overview
+@page example-index Examples
+@page tips Tips and tricks
+@page utilities Utilities
+@page opengl OpenGL
+@page openal OpenAL
+@page debugoperators Debug output operators for custom types
+@page configurationvalues Configuration value parsers and writers for custom types
+@page deprecated Deprecated list
+@page coding-style Coding style
+
+@page changelog Changelog
+@page changelog-plugins Plugins changelog
+@page changelog-integration Integration changelog
+@page changelog-extras Extras changelog
+@page changelog-examples Examples changelog
+
+*/

doc/opengl.dox

@@ -37,6 +37,12 @@ following table.
 
 -   @subpage opengl-support
 
+Some OpenGL APIs are marked as deprecated, as they are superseded by newer
+functionality. You may still need to use them to support older hardware, but in
+general they should be avoided.
+
+-   @subpage opengl-deprecated
+
 @section opengl-required-extensions Version and extension requirements
 
 The engine requires at least OpenGL 2.1 or OpenGL ES 2.0, but some specific