Add support for Apple's Accelerate sparse matrix solvers

Eigen/AccelerateSupport

@@ -0,0 +1,53 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// 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/.
+
+#ifndef EIGEN_ACCELERATESUPPORT_MODULE_H
+#define EIGEN_ACCELERATESUPPORT_MODULE_H
+
+#include "SparseCore"
+
+#include "src/Core/util/DisableStupidWarnings.h"
+
+/** \ingroup Support_modules
+  * \defgroup AccelerateSupport_Module AccelerateSupport module
+  *
+  * This module provides an interface to the Apple Accelerate library.
+  * It provides the seven following main factorization classes:
+  * - class AccelerateLLT: a Cholesky (LL^T) factorization.
+  * - class AccelerateLDLT: the default LDL^T factorization.
+  * - class AccelerateLDLTUnpivoted: a Cholesky-like LDL^T factorization with only 1x1 pivots and no pivoting
+  * - class AccelerateLDLTSBK: an LDL^T factorization with Supernode Bunch-Kaufman and static pivoting
+  * - class AccelerateLDLTTPP: an LDL^T factorization with full threshold partial pivoting
+  * - class AccelerateQR: a QR factorization
+  * - class AccelerateCholeskyAtA: a QR factorization without storing Q (equivalent to A^TA = R^T R)
+  *
+  * \code
+  * #include <Eigen/AccelerateSupport>
+  * \endcode
+  *
+  * In order to use this module, the Accelerate headers must be accessible from
+  * the include paths, and your binary must be linked to the Accelerate framework.
+  * The Accelerate library is only available on Apple hardware.
+  * 
+  * Note that many of the algorithms require additional information about your
+  * matrices. This can be provided by setting the UpLo template argument when
+  * defining the factorization class. For example, the following creates an
+  * LDLT factorization where your matrix is symmetric and uses the lower
+  * triangle:
+  * 
+  * \code
+  * AccelerateLDLT<SparseMatrix<float>, Lower | Symmetric> ldlt;
+  * \endcode
+  * 
+  * Failure to do so may result in your application crashing.
+  */
+
+#include "src/AccelerateSupport/AccelerateSupport.h"
+
+#include "src/Core/util/ReenableStupidWarnings.h"
+
+#endif // EIGEN_ACCELERATESUPPORT_MODULE_H