Announcing TypeScript 2.6 RC

I was concerned that it would be difficult to use the new `--strictFunctionTypes` flag due to all the 3rd party typings not conforming to this flag. However, sandersn fixed[0] many popular packages not long after this feature landed.

I've been using TypeScript for 5 years[1] and it has been a great experience,! Even these (occasional) "breaking" changes are relatively easy to navigate.

[0]: https://github.com/Microsoft/TypeScript/pull/18654#issuecomm...

[1]: https://blogs.msdn.microsoft.com/typescript/2017/10/02/types...