Jelle Zijlstra bdb06b5b81 improve codecs stubs (#2114) ...

Started out as progress towards #1476, but I ended up fixing a few more things:
- fixed the signature of _encode_type, which actually returns a pair, not a string
- made some attributes into properties in order to prevent the descriptor protocol from turning them into methods
- found a bug in CPython in the process (python/cpython#6779)

I used the following test file to make sure these classes are now instantiable:

```python
import codecs
import io
from typing import IO

bio = io.BytesIO()
cod = codecs.lookup('utf-8')

codecs.StreamReaderWriter(bio, codecs.StreamReader, codecs.StreamWriter)
codecs.StreamRecoder(bio, cod.encode, cod.decode, codecs.StreamReader, codecs.StreamWriter)
```

2018-06-11 15:53:15 -07:00

..

2

fix type for itertools.product (#2129)

2018-06-11 15:52:44 -07:00

2and3

improve codecs stubs (#2114)

2018-06-11 15:53:15 -07:00

3

fix type for itertools.product (#2129)

2018-06-11 15:52:44 -07:00

3.3

make BZ2File and LZMAFile instantiable (#2115)

2018-06-11 13:59:38 -07:00

3.4

Improve asyncio.tasks stubs (#2139)

2018-06-11 14:40:54 -07:00

3.5

more 3.7 features (#2015)

2018-04-06 11:09:11 -07:00

3.6

Make some arguments in secrets module optional (#1929)

2018-02-27 10:52:21 -08:00

3.7

make contextvars.Context instantiable (#2119)

2018-06-11 14:03:02 -07:00