Negated types

Sometimes it is desired to forbid certain types from being considered.

Example: `JSON.stringify(function() {});` doesn't make sense and the chance is high it's written like this by mistake. With negated types we could eliminate a chance of it.

``` typescript
type Serializable = any ~ Function; // or simply ~ Function
declare interface JSON {
stringify(value: Serializable): string;
}
```

Another example

``` typescript

export NonIdentifierExpression = ts.Expression ~ ts.Identifier

```

No files, tests, or entry points are named. Start by reviewing the proposed Serializable and NonIdentifierExpression examples, then determine the required type-system behavior and its effects on assignability; done means negated types are supported consistently and covered by appropriate tests.

Written by the indexing model from the issue text.