OdtDocument interface cleanup

As part of some other work I noticed these functions exposed on ```OdtDocument``` that didn't make sense to me as they were just wrapping functions provided by ```OdfUtils``` or ```odf.Formatting```. My assumption is that they are some left overs from earlier refactoring work so I have removed these functions from ```OdtDocument``` and changed the classes using them to use the functions directly off the classes that provide them.

I think this is an improvement as initially if you are not familiar with the system it was easy to use these functions on ```OdtDocument``` by mistake. It also makes it easier to do any future refactoring that may affect these methods.
Please:
`getDefaultAttributes` -> `includeSystemDefault` or `inheritSystemDefault`
`!styleName` -> explicit `styleName === ""`for consistency with similar checks