supported Unicode characters in Python 2

According to the note of [curses library documentation](https://docs.python.org/2/library/curses.html):

1. locale is required to be set and
2. the Unicode character to be encoded with the set encoding.

Following the note, using the system's default encoding and encoding the strings. `addch` is replaced with `addstr` since multiple characters of encoded Unicode character are needed to be added.