Added tridiagonal matrix unit tests.

src/UnitTests/Matrices/TridiagonalMatrixTest.cpp

 /***************************************************************************
-                          DenseMatrixTest.cpp -  description
+                          TridiagonalMatrixTest.cpp -  description
                              -------------------
-    begin                : Nov 10, 2018
-    copyright            : (C) 2018 by Tomas Oberhuber et al.
+    begin                : Jan 8, 2020
+    copyright            : (C) 2020 by Tomas Oberhuber et al.
     email                : tomas.oberhuber@fjfi.cvut.cz
  ***************************************************************************/
 
 /* See Copyright Notice in tnl/Copyright */
 
-#include "DenseMatrixTest.h"
\ No newline at end of file
+#include "TridiagonalMatrixTest.h"
\ No newline at end of file

src/UnitTests/Matrices/TridiagonalMatrixTest.cu

 /***************************************************************************
-                          DenseMatrixTest.cu -  description
+                          TridiagonalMatrixTest.cu -  description
                              -------------------
-    begin                : Nov 10, 2018
-    copyright            : (C) 2018 by Tomas Oberhuber et al.
+    begin                : Jan 8, 2020
+    copyright            : (C) 2020 by Tomas Oberhuber et al.
     email                : tomas.oberhuber@fjfi.cvut.cz
  ***************************************************************************/
 
 /* See Copyright Notice in tnl/Copyright */
 
-#include "DenseMatrixTest.h"
\ No newline at end of file
+#include "TridiagonalMatrixTest.h"
\ No newline at end of file