SiTCP 10G implementation

[cbespin]

@MarcoVogt There is a three-year old branch called SiTCP_10G that has not been merged with some remaining changes. Can those be merged safely and/ or is something missing to provide proper 10G support?
I would like to clean up the repository a bit, and the example on the named branch looks very useful as well. Before merging, I would like to have the functionality as complete as possible. I know there are some implementations of 10G firmwares around but not what the status concerning their stability is.

I am considering a new major release at a undetermined time where we can include as much as possible for 10G support.