reset stdout in prequeue.py near end

Other output shouldn't be dumped into items/item_attributes.tx by
default.

prequeue.py

@@ -13,11 +13,16 @@ def main():
     macros = preprocessor.load_pokecrystal_macros()
     macro_table = preprocessor.make_macro_table(macros)
 
+    stdout = sys.stdout
+
     for source in sys.argv[1:]:
         dest = os.path.splitext(source)[0] + '.tx'
         sys.stdin  = open(source, 'r')
         sys.stdout = open(dest, 'w')
         preprocessor.preprocess(macro_table)
 
+    # reset stdout
+    sys.stdout = stdout
+
 if __name__ == '__main__':
     main()