Move Doxygen-only stuff to *.dox

Eigen/Core

diff --git a/Eigen/Core b/Eigen/Core
index 3f1efb5..16e388f 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -220,9 +220,6 @@
 /** \brief Namespace containing all symbols from the %Eigen library. */
 namespace Eigen {
 
-/** \brief Namespace containing low-level routines from the %Eigen library. */
-namespace internal {}
-
 inline static const char *SimdInstructionSetsInUse(void) {
 #if defined(EIGEN_VECTORIZE_AVX)
   return "AVX SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2";

doc/Manual.dox

diff --git a/doc/Manual.dox b/doc/Manual.dox
index 0cbe792..d6d4d46 100644
--- a/doc/Manual.dox
+++ b/doc/Manual.dox
@@ -159,4 +159,7 @@
     \ingroup Geometry_Reference */
 /** \addtogroup Splines_Module
     \ingroup Geometry_Reference */
+
+/** \brief Namespace containing low-level routines from the %Eigen library. */
+namespace internal {}
 }

unsupported/Eigen/doxygen.hpp

diff --git a/unsupported/Eigen/doxygen.hpp b/unsupported/Eigen/doxygen.hpp
deleted file mode 100644
index 0314885..0000000
--- a/unsupported/Eigen/doxygen.hpp
+++ /dev/null
@@ -1,19 +0,0 @@
-// This file is part of Eigen, a lightweight C++ template library
-// for linear algebra.
-//
-// Copyright (C) 2014 Chen-Pang He <jdh8@ms63.hinet.net>
-//
-// This Source Code Form is subject to the terms of the Mozilla
-// Public License v. 2.0. If a copy of the MPL was not distributed
-// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// As its name suggests, this file is intended to be read by Doxygen.
-// There is nothing defined so we need no #include guard.
-
-//! \brief Namespace containing all symbols from the %Eigen library.
-namespace Eigen {
-
-//! \brief Namespace containing low-level routines from the %Eigen library.
-namespace internal {}
-
-}

unsupported/doc/Overview.dox

diff --git a/unsupported/doc/Overview.dox b/unsupported/doc/Overview.dox
index d048377..93b2a89 100644
--- a/unsupported/doc/Overview.dox
+++ b/unsupported/doc/Overview.dox
@@ -1,3 +1,4 @@
+/// \brief Namespace containing all symbols from the %Eigen library.
 namespace Eigen {
 
 /** \mainpage Eigen's unsupported modules
@@ -22,4 +23,6 @@
 
 */
 
+/// \brief Namespace containing low-level routines from the %Eigen library.
+namespace internal {}
 }