Add Context Support

[freeformz]

This is to track support for this https://go-review.googlesource.com/c/29381/

[freeformz]

golang/go#15123 is closed and this has landed in master as golang/go@e13df02

[freeformz]

See also: https://go-review.googlesource.com/#/c/30166/

@johto @uhoh-itsmaciek You may want to take a look at that CL if interested.

[itsjamie]

#531 is related

[maddyblue]

I'm actively working on this but don't have a full PR ready yet. If someone else has interest I'm happy to coordinate.

[itsjamie]

@mjibson I was planning on working on one of the tickets I've linked to through #531, it looks like a lot of it runs through the new context-based API. I'd be happy to work with you if you've got something you can split off for me to work on.

[maddyblue]

I've just got this working so I'll send a PR soon. Need to write some tests first.

[nathany]

With #535 merged, is this issue closed?

[tamird]

Yep!