Add comprehensive tests for Unmarshal and Decoder.
Add comprehensive tests for Unmarshal and Decoder.

postfix/go-xdr,davecgh/go-xdr,dajohi/go-xdr,nullstyle/go-xdr,rasky/go-xdr,postfix/go-xdr,dajohi/go-xdr,rasky/go-xdr,nullstyle/go-xdr,davecgh/go-xdr