Made fmatrix.hh totally independet of istl.

Before it included headers from istl.
Moved precision.hh to dune/common.

[[Imported from SVN: r212]]

istl/precision.hh

-// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
-// vi: set et ts=4 sw=2 sts=2:
-#ifndef __DUNE_PRECISION_HH__
-#define __DUNE_PRECISION_HH__
-
-#include <stdlib.h>
-
-namespace Dune {
-
-  /**
-              @addtogroup ISTL
-              @{
-   */
-
-  template <class ctype = double>
-  class ISTLPrecision {
-  public:
-    //! return threshold to do pivoting
-    static ctype pivoting_limit ()
-    {
-      return _pivoting;
-    }
-
-    //! set pivoting threshold
-    static void set_pivoting_limit (ctype pivthres)
-    {
-      _pivoting = pivthres;
-    }
-
-    //! return threshold to declare matrix singular
-    static ctype singular_limit ()
-    {
-      return _singular;
-    }
-
-    //! set singular threshold
-    static void set_singular_limit (ctype singthres)
-    {
-      _singular = singthres;
-    }
-
-    //! return threshold to declare matrix singular
-    static ctype absolute_limit ()
-    {
-      return _absolute;
-    }
-
-    //! set singular threshold
-    static void set_absolute_limit (ctype absthres)
-    {
-      _absolute = absthres;
-    }
-
-  private:
-    // just to demonstrate some state information
-    static ctype _pivoting;
-    static ctype _singular;
-    static ctype _absolute;
-  };
-
-  template <class ctype>
-  ctype ISTLPrecision<ctype>::_pivoting = 1E-8;
-  template <class ctype>
-  ctype ISTLPrecision<ctype>::_singular = 1E-14;
-  template <class ctype>
-  ctype ISTLPrecision<ctype>::_absolute = 1E-80;
-
-  /** @} end documentation */
-
-} // end namespace
-
-#endif