fat_io_lib finally works, implement virtual partition devices, manage devices via string keys

ce/ce.c

@@ -302,6 +302,9 @@ static void ls (const char* path_string) {
   }
 
   size_t entries = desc.size;
+  printf ("total entries: %zu\n", entries);
+  printf ("\n");
+
   for (size_t entry_num = 0; entry_num < entries; entry_num++) {
     read_dir_entry (path, &entry, entry_num);
     describe (entry.path, &desc);