Support for XML Serialization

[anotherhale]

I understand that the name of the project is xtract and that it focuses on XML deserialization, but there is no support for XML serialization. Have you explored supporting serialization? I have not seen any great Scala libraries that support XML serialization the way that xtract does deserialization. I would love to leverage the deserialization code that I have written with xtract and also be able to do serialization.

[tmccombs]

I've thought about it a little bit. I didn't have a use case for serialization. But I if that would be useful I can look into implementing it.

[anotherhale]

I may be able to assist. I will have to see what my work says about the current implementation and if we go an entire different direction or I have asked to keep using Xtract and to implement serialization.

[anotherhale]

I actually wrote an Either type modeled after the Play JSON library implementation that I have been meaning to open a pull request for. I will try to do that soon.

[anotherhale]

I also have README update and example code for supporting case classes with more than 22 parameters/fields.

[anotherhale]

Sorry forgot about this. I will try to dig through my code and see if I still have this.