In this commit onion routing error from BOLT#4 have been added, the
initial error construction have been splitted on two parts: The first
part which contains the actual data will reside inside the lnwire
package because it contains all necessary function to decode/encode
the data. The second part obfuscation and hmac checking will resides
inside the lighting-onion package because it requires the key
generation.
Andrey Samokhvalov