Fix reading time at t=t final

When reading the particles, I am always opening 2 index files. One before the requested time and one after (for the history). Currently, if you are asking for the final time, the code will open the last index file and will try with the "next" one. Therefore I need to add a special case for the final time.

Fix #739 (closed)

logger/logger_reader.c

@@ -156,6 +156,11 @@ void logger_reader_set_time(struct logger_reader *reader, double time) {
     }
   }
 
+  /* Deal with the final time */
+  if (left == (unsigned int) reader->index.n_files - 1) {
+    left -= 1;
+  }
+
   /* Generate the filename */
   char filename_prev[STRING_SIZE + 50];
   sprintf(filename_prev, "%s_%04u.index", reader->basename, left);