typedef members have no memberof

**If you're reporting a bug, please include _input code_, _output documentation_,
a description of what you expected to happen, and what happened instead.**

Typedef members do not get a `memberof` property. If iterating over the properties it's not possible to associate it back to the owning typedef. Other properties (such as on objects) do have `memberof`.

Input code:

```
/**
* A typedef
*
* @typedef {Object} myTypedef
* @property {String} type - The type
*/
```

Output:

```
{
"title": "property",
"name": "type",
"lineNumber": 4,
"description": {
....
},
"type": {
"type": "NameExpression",
"name": "String"
}
}
```

* What version of documentation.js are you using?: 4.0.0
* How are you running documentation.js (on the CLI, Node.js API, Grunt, other?): cli, node