[psLib] make PSTokenizer indipendent StringIO-like object; fix issues with python3 (bytes vs unicode)
[psLib] make PSTokenizer indipendent StringIO-like object; fix issues with python3 (bytes vs unicode)

PSTokenizer is now an indipendent object behaving like a StringIO.StringIO: it has `read` and `close` methods, as well as `buf`, `pos` and `len` attributes.

The input data is a string of bytes, and the output tokens are ascii-decoded unicode strings.

(I removed "__main__" as it was using a non-py23 EasyDialogs module)

See https://github.com/behdad/fonttools/issues/393.

Related to https://github.com/behdad/fonttools/issues/391.

fonttools/fonttools,googlefonts/fonttools