(main|file-handler)~fixed some stuff

Big bug with file handler: I can write data well, but reading it
causes some trace error which I cannot be bothered to fix.  So I'll
just work on making the step function way more efficient.

main.c

@@ -116,9 +116,12 @@ int main(void)
   }
 
   if (state.thread_alive)
-    pthread_cancel(step_thread);
+  {
+    state.thread_alive = false;
+    pthread_join(step_thread, NULL);
+  }
 
-  write_to_file(&state, "data.out");
   CloseWindow();
+  free(state.data);
   return 0;
 }