Add 'types' property to package.json
Add 'types' property to package.json

As recommended on https://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html

Closes https://github.com/KeesCBakker/Strongly-Typed-Events-for-TypeScript/issues/3
KeesCBakker/Strongly-Typed-Events-for-TypeScript,KeesCBakker/Strongly-Typed-Events-for-TypeScript,KeesCBakker/Strongly-Typed-Events-for-TypeScript