Accidentally using Language constructor breaks hash values

[doktoren]

I ran into the problem that

>>> Language("da") == Language.get("da")
True
>>> Language("da") in {Language.get("da")}
False

I know that the Language constructor specifies that It's inefficient to call this directly but it doesn't clearly say not to call it directly. And it's an easy mistake to do when it otherwise seems to work fine.

It seems that problem could easily be fixed by updating

    def __hash__(self) -> int:
        return hash(id(self))

to

    def __hash__(self) -> int:
        return hash(self._str_tag)

but I have no idea if other parts of the code doesn't work as expected either when calling the Language constructor directly.