RFC: Semantic Versioning for TypeScript Types

This RFC proposes a definition of [Semantic Versioning][semver] for
managing changes to TypeScript types, including when the TypeScript
compiler makes breaking changes in its type-checking and type emit
across a “minor”release.(Note that this RFC addresses *only* type
checking and type emit, *no t* the “transpilation”mode of the TypeScript
compiler.)

[semver]: https://semver.org

While this RFC is being authored in the context of Ember.js’ [adoption
of TypeScript as a first-cl ass supported language][RFC], its
recommendations are intentionally general, in hopes that th ese
recommendations can be widely adopted by the broader TypeScript
community.

[RFC]: #724