Fixed file output directory.

- This fix is very minimal, as a result output directory arguments
    must have a trailing slash.

Fixes #34

dsd_main.c

@@ -103,6 +103,7 @@ initOpts (dsd_opts * opts)
   opts->playoffset = 0;
   opts->mbe_out_dir[0] = 0;
   opts->mbe_out_file[0] = 0;
+  opts->mbe_out_path[0] = 0;
   opts->mbe_out_f = NULL;
   opts->audio_gain = 0;
   opts->audio_out = 1;