Expand typescript checks

[shadowspawn]

Pull Request

Problem

1. The TypeScript tests are weakened by the options stored as properties, meaning random properties do not cause errors.

[key: string]: any; // options as properties

program.silly; // <-- might be a property...

2. The testing coverage is a bit uneven, consisting mostly of examples from the README and the example files.

Solution

1. Use some TypeScript magic to strip the options out of the Command type and use CommandWithoutOptionsAsProperties for most of the testing.

2. Methodically test the variations of what is declared in the TypeScript.

[abetomo]

awesome 👍