Added a basic initializer which sets options to 0.

If we don't set the options to 0, the writer does not get initialized correctly.
In particular, in the test I added, the result will show up a

    <?xml version=\"1.0\" encoding=\"UTF-8\"?><theTag>theContent</>

Note the `</>` where we would expect `</theTag>`.
Honored pull request from angelos which made [[TCMXMLWriter alloc] init]/[TCMXMLWriter new] work as well. (was broken before)