Fix integration with mass and add VTK output

Signed-off-by: Rafael Ravedutti <rafaelravedutti@gmail.com>

src/includes/parameter.h

@@ -35,6 +35,7 @@
 typedef struct {
     int force_field;
     char* input_file;
+    char* vtk_file;
     MD_FLOAT epsilon;
     MD_FLOAT sigma6;
     MD_FLOAT temp;

src/includes/vtk.h

@@ -0,0 +1,28 @@
+/*
+ * =======================================================================================
+ *
+ *   Author:   Jan Eitzinger (je), jan.eitzinger@fau.de
+ *   Copyright (c) 2020 RRZE, University Erlangen-Nuremberg
+ *
+ *   This file is part of MD-Bench.
+ *
+ *   MD-Bench is free software: you can redistribute it and/or modify it
+ *   under the terms of the GNU Lesser General Public License as published
+ *   by the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   MD-Bench is distributed in the hope that it will be useful, but WITHOUT ANY
+ *   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ *   PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ *   details.
+ *
+ *   You should have received a copy of the GNU Lesser General Public License along
+ *   with MD-Bench.  If not, see <https://www.gnu.org/licenses/>.
+ * =======================================================================================
+ */
+#include <atom.h>
+
+#ifndef __VTK_H_
+#define __VTK_H_
+extern int write_atoms_to_vtk_file(const char* filename, Atom* atom, int timestep);
+#endif