Support for TypeScript 4.0

[millsp]

You can now enjoy the most optimized version of ts-toolbelt. Besides countless internal optimizations from my side, the TypeScript team has been working on many ways to improve the type system. This has led to some of the most exciting and awaited features:

• Variadic Tuple Types
  This means a lot of optimization for this library, not having to emulate Concat anymore.
• Recursive Type Aliases
  We pushed hard for the use of recursive types. I'm very happy to announce that this is officially supported now.
• The TypeScript team has also been working relentlessly on improving performance. And this is something that we can clearly feel on this latest release -- Cutting the type count by 60% for the ts-toolbelt!

Besides that, there will be breaking changes on this version:

• MergeUp is now called Merge
• Merge is now called Patch
• Some API's have changed, not very used ones though.

Why ts-toolbelt@8 instead of 7? I only like odd numbers! No. Just a bug with the automated versioning... Not worth my time.

[mesqueeb]

nice!!!