JSDoc
Gets and sets the basename of `file.path`.
Throws when `file.path` is not set.
Example:
```js
var file = new File({
cwd: '/',
base: '/test/',
path: '/test/file.js'
});
console.log(file.basename); // file.js
file.basename = 'file.txt';
console.log(file.basename); // file.txt
console.log(file.path); // /test/file.txt
```