Porting to Python 3

Sgfmill is a Python 3 version of the SGF code from the Gomill project.

The differences are as follows:

There is a new Sgf_game.from_bytes() classmethod, which behaves like the old Sgf_game.from_string().

Sgf_game.from_string() now expects a Python 3 string (which contains Unicode characters), and forces the game’s encoding to UTF-8.

Sgf_game.serialise() now returns a bytes object.

Tree_node.get_raw() and Tree_node.set_raw() (and related methods) now use bytes objects.

For Text and SimpleText properties, Tree_node.get() and Tree_node.set() use Python 3 strings.

The exact rules for what ‘raw’ data is accepted for some property types have changed, due to changes in the Python language features used to implement the parser. In particular:

• CESU-8 is no longer accepted when parsing data which purports to be UTF-8.
• The raw values accepted for properties of type Real are now determined by Python 3’s float() function rather than the platform libc (exactly what is accepted will depend on the Python minor version).
• The interpreter for type Number is more lenient, accepting spaces anywhere in the string, and ‘grouping underscores’ from Python 3.6 on.