add types to logging

[tharvik]

Add types to the logging module, in a python 2-3 compatible version.

[gvanrossum]

That's a lot of code... I will have to check whether it really works. If I find a flaw I can't quickly fix I may have to roll back. But for now, benefit of the doubt. Thanks!

[gvanrossum]

I found a few things.

• instead of TextIO, it should use IO[str](since sys.stdout is the latter in 2.7)
• lots of code uses logging.WARN instead of logging.WARNING. I fixed these in d75e2ab

A few more I'm not sure whether to fix:

• the message argument to error() etc. can be unicode in Python 2
• the message argument to error() etc. can be a non-string (apparently str() is applied somewhere)
• there are undocumented public-seeming attributes that are commonly used, e.g. Logger.level

I think I'll fix the unicode one (it's easy to use typing.Text instead) but I'm not sure about the others. It's true these are undocumented but if they are actual behavior that lots of code relies on I think we may have to add them.

[gvanrossum]

Also, log() takes an initial argument lvl: int -- I'll add this while I'm at it.

Done: 8ee3123

[tharvik]

• lots of code uses logging.WARN instead of logging.WARNING.
• there are undocumented public-seeming attributes that are commonly used, e.g. Logger.level

Theses codes are wrong, sadly, but for now, I'll add them. Do you have a list of wanted attributes?

• the message argument to error() etc. can be unicode in Python 2

Let's switch to Text then.

• the message argument to error() etc. can be a non-string (apparently str() is applied somewhere)

And from Text, here goes Any. But it is still wrong code (which, in a way, is supposed to be found by mypy).

[gvanrossum]

I fixed the one place I found that used logger.level in our code; I think it's pretty clear they were just taking a shortcut.

Regarding the message argument, I think it should be Text everywhere (and I've already made it that -- it should work because Text is defined in typing.pyi in typeshed, even though it's not yet in most runtimes since we're waiting for 3.5.2 to push out a new version).