split the Sparse module into multiple ones, and move non stable parts to unsupported/

(see the ML for details)

unsupported/Eigen/SparseExtra

@@ -0,0 +1,67 @@
+#ifndef EIGEN_SPARSE_EXTRA_MODULE_H
+#define EIGEN_SPARSE_EXTRA_MODULE_H
+
+#include "../Eigen/Sparse"
+
+#include "src/Core/util/DisableMSVCWarnings.h"
+
+#include <vector>
+#include <map>
+#include <cstdlib>
+#include <cstring>
+#include <algorithm>
+
+#ifdef EIGEN_GOOGLEHASH_SUPPORT
+  #include <google/dense_hash_map>
+#endif
+
+namespace Eigen {
+
+/** \defgroup SparseExtra_Module SparseExtra module
+  *
+  * This module contains some experimental features extending the sparse module.
+  *
+  * \code
+  * #include <Eigen/SparseExtra>
+  * \endcode
+  */
+
+enum SparseBackend {
+  DefaultBackend,
+  Taucs,
+  Cholmod,
+  SuperLU,
+  UmfPack
+};
+
+// solver flags
+enum {
+  CompleteFactorization       = 0x0000,  // the default
+  IncompleteFactorization     = 0x0001,
+  MemoryEfficient             = 0x0002,
+
+  // For LLT Cholesky:
+  SupernodalMultifrontal      = 0x0010,
+  SupernodalLeftLooking       = 0x0020,
+
+  // Ordering methods:
+  NaturalOrdering             = 0x0100, // the default
+  MinimumDegree_AT_PLUS_A     = 0x0200,
+  MinimumDegree_ATA           = 0x0300,
+  ColApproxMinimumDegree      = 0x0400,
+  Metis                       = 0x0500,
+  Scotch                      = 0x0600,
+  Chaco                       = 0x0700,
+  OrderingMask                = 0x0f00
+};
+
+#include "src/SparseExtra/RandomSetter.h"
+#include "src/SparseExtra/SparseLLT.h"
+#include "src/SparseExtra/SparseLDLT.h"
+#include "src/SparseExtra/SparseLU.h"
+
+} // namespace Eigen
+
+#include "src/Core/util/EnableMSVCWarnings.h"
+
+#endif // EIGEN_SPARSE_EXTRA_MODULE_H