message: Fixed some documentation errors in coefficient.
diff: @@ -404,7 +404,7 @@ public:
  : VectorCoefficient(v.Size()), vec(v) { }
  using VectorCoefficient::Eval;
  - /// Evaluate the vector coefficient at @ip.
  + /// Evaluate the vector coefficient at @a ip.
  virtual void Eval(Vector &V, ElementTransformation &T,
  const IntegrationPoint &ip) { V = vec; }
  };
  @@ -674,7 +674,7 @@ public:
  : VectorCoefficient(vc.GetVDim())
  { c = &vc; attr.Copy(active_attr); }
  - /// Evaluate the vector coefficient at @ip.
  + /// Evaluate the vector coefficient at @a ip.
  virtual void Eval(Vector &V, ElementTransformation &T,
  const IntegrationPoint &ip);
  @@ -737,7 +737,7 @@ public:
  MatrixConstantCoefficient(const DenseMatrix &m)
  : MatrixCoefficient(m.Height(), m.Width()), mat(m) { }
  using MatrixCoefficient::Eval;
  - /// Evaluate the matrix coefficient at @ip.
  + /// Evaluate the matrix coefficient at @a ip.
  virtual void Eval(DenseMatrix &M, ElementTransformation &T,
  const IntegrationPoint &ip) { M = mat; }
  };
  @@ -786,7 +786,7 @@ public:
  mat.SetSize(0);
  }
  - /// Evaluate the matrix coefficient at @ip.
  + /// Evaluate the matrix coefficient at @a ip.
  virtual void Eval(DenseMatrix &K, ElementTransformation &T,
  const IntegrationPoint &ip);
  