Added constness to flags

doc/author_andreev.txt

@@ -0,0 +1 @@
+I place my contributions to t8code under the FreeBSD license. Evgenii Andreev ([email protected])

src/t8_forest/t8_forest.c

@@ -1445,14 +1445,14 @@ t8_forest_compute_elements_offset (t8_forest_t forest)
 int
 t8_forest_write_vtk_ext (t8_forest_t forest,
                          const char *fileprefix,
-                         int write_treeid,
-                         int write_mpirank,
-                         int write_level,
-                         int write_element_id,
-                         int write_ghosts,
-                         int write_curved,
+                         const int write_treeid,
+                         const int write_mpirank,
+                         const int write_level,
+                         const int write_element_id,
+                         const int write_ghosts,
+                         const int write_curved,
                          int do_not_use_API,
-                         int num_data, t8_vtk_data_field_t *data)
+                         const int num_data, t8_vtk_data_field_t *data)
 {
   T8_ASSERT (forest != NULL);
   T8_ASSERT (forest->rc.refcount > 0);

src/t8_forest/t8_forest_io.h

@@ -73,14 +73,14 @@ void                t8_forest_save (t8_forest_t forest);
  */
 int                 t8_forest_write_vtk_ext (t8_forest_t forest,
                                              const char *fileprefix,
-                                             int write_treeid,
-                                             int write_mpirank,
-                                             int write_level,
-                                             int write_element_id,
-                                             int write_ghosts,
-                                             int write_curved,
+                                             const int write_treeid,
+                                             const int write_mpirank,
+                                             const int write_level,
+                                             const int write_element_id,
+                                             const int write_ghosts,
+                                             const int write_curved,
                                              int do_not_use_API,
-                                             int num_data,
+                                             const int num_data,
                                              t8_vtk_data_field_t *data);
 
 /** Write the forest in a parallel vtu format. Writes one master