Fix LongCode and IntCode

Great library, thanks for making it.  

The roundtrip test wasn't actually checking that the resulting decoded value was equal to the input and so the Long and Int codecs were not encoding/decoding correctly.  I fixed the roundtrip function and was also able to fix the Long and Int code, but I could only fix the codecs when the bit-size aligned with the byte boundary such as uint4, uint8, etc.  For uint2 and the like I think decoding needs to do something with nibbles, to slice the byte as needed, but I am not the best bit twiddler out there so I could be wrong.