1.0.0

As you'd expect from a major version change, this is API-incompatible
with 0.2.0. Most critically, one now needs to consider that Option<T> is
passed back from Tag methods.

- Add File::new_type
- Add tests
- Allow File::new to take anything that can become a Path
- Fix CString usages for newer Rust compilers (see issue #3, thanks @fabian-z)
- Fix potential dangling pointer (see issue #1, thanks @czipperz)
- Remove taglib_sys::set_strings_unicode interfaces
- Use MIT/X11 license
- Use Option<T> for missing fields (see #8, thanks @kalouantonis)

TagLib-Rust 0.1.0