Improve typings
Improve typings

Follow recommendations from DefinitelyTyped (https://www.typescriptlang.org/docs/handbook/declaration-files/templates/module-function-d-ts.html).

Fixes error in Typescript triggered in the following code:
    import moize from "moize";
    export memoize = moize.maxSize(5);

Error: "Exported variable 'memoize' has or is using name 'Options' from external module '...' but cannot be named"
planttheidea/moize,planttheidea/moize