Implemented a new i/o scheme where each MPI ranks writes a file instead of...

Implemented a new i/o scheme where each MPI ranks writes a file instead of writing a single file for all the ranks.

src/distributed_io.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2019 Matthieu Schaller (schaller@strw.leidenuniv.nl)
+ *
+ * This program 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.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_DISTRIBUTED_IO_H
+#define SWIFT_DISTRIBUTED_IO_H
+
+/* Config parameters. */
+#include "../config.h"
+
+#if defined(HAVE_HDF5) && defined(WITH_MPI)
+
+/* MPI headers. */
+#ifdef WITH_MPI
+#include <mpi.h>
+#endif
+
+/* Includes. */
+#include "engine.h"
+#include "io_properties.h"
+#include "part.h"
+#include "units.h"
+
+void write_output_distributed(struct engine* e, const char* baseName,
+                              const struct unit_system* internal_units,
+                              const struct unit_system* snapshot_units,
+                              int mpi_rank, int mpi_size, MPI_Comm comm,
+                              MPI_Info info);
+
+#endif /* HAVE_HDF5 && WITH_MPI */
+
+#endif /* SWIFT_DISTRIBUTED_IO_H */