bpo-29728: Provide socket.TCP_NOTSENT_LOWAT

[njsmith]

New TCP option available on recent MacOS and Linux.

[alex]

This should probably be documented in socket.rst

[Mariatta]

Please create a ticket in bugs.python.org to track this :)

[njsmith]

@alex: good point, done.

@Mariatta: https://bugs.python.org/issue29728

[Mariatta]

@njsmith seems like there's trailing whitespace issue with the docs change 😅

Will you be able to fix it? (see travis output)

[Mariatta]

I think this should be added to Misc/NEWS too.

[njsmith]

@Mariatta: whoops, I somehow missed the notification on your earlier comments. Thanks for fixing things up!

[Mariatta]

Well... in my attempt to clean this however... I actually messed up your branch 😅 Sorry about this. I will try to clean it up later..

[njsmith]

Rebased and cleaned up

[njsmith]

no idea what that travis failure is about

[Mariatta]

Thanks @njsmith :)

I think the travis failure is a separate matter, tracked in python/core-workflow#54