Support AsRef instead of &Path for path parameters#3

Would it be possible to change the definition of the `Args` struct from `&'a [&'a Path]` to something like `&'a [P]` `where P: AsRef<Path>`? I have a `Vec<PathBuf>` that comes from reading a config file. I would like to be able to just pass it to flatc as `Args{ inputs: &inputs[..], ... }`. Thanks :)