Add support for typescript 2.3 about dtslint

We generally wait until a month after a release before changing any packages on DefinitelyTyped. This gives people time to upgrade to the new TypeScript version before packages start requiring it.
Based on that we should enable ts2.3 support on May 27.

[CaselIT]

Thanks for the info @andy-ms
I was not aware of this practice.
Do you prefer if I close che PR on DT and reopen them in a month time, or should I just leave them open?

It's up to you.

[CaselIT]

Ok, I'll leave them open and reference this issue.

Thanks

[DanielRosenwasser]

Do we have to have this rule in place across all packages instead of just existing ones? Seems like if a declaration file doesn't exist, there's no reason to keep the restriction in place.

That would be nice but the way dtslint is designed, it doesn't distinguish between new/changed packages. I guess we could edit types-publisher to just look for the string // TypeScript Version: 2.3 on changed packages only, and have failures through that instead of dtslint.

[DanielRosenwasser]

Yes, dtslint just failing on the header is likely confusing to contributors anyway.

[CaselIT]

Shouldn't this waiting period be implemented in the type publisher?
According to the header it could only update the definition after the month, or alternatively it could publish the updated definition on a next tag in npm and update the latest tag only after a month.
This would avoid a large number of open PR on DT waiting for the end of waiting period and if the next tag is used it would allow users to use the latest definitions if they so choose

I can open a related issue on https://github.com/Microsoft/types-publisher if it's more appropriate