Fix short address decoding

[k06a]

Example addresses:

0x0014F55A50b281EFD12294f0Cda821Bd8171e920
0x0000000000000000000000000000000000000000

[Shirikatsu]

Thanks for your pull request @k06a!

I'm unsure in which scenario an address would not be 20 bytes in length. What did you have in mind for this change?

[k06a]

@Shirikatsu at some moment of time client encoder may encode addresses as numbers and this may lead to zero bytes prefix compression for some addresses, containing first zero bytes. Address encoded this way will be absolutely legal, I just want to ensure smart contract will support this case.

[maxrobot]

@k06a this change is probably better directed at the project https://github.com/androlo/standard-contracts/blob/master/contracts/src/codec/RLP.sol

Thank you for you contribution nonetheless.

Have you managed to use Ion in any meaningful way, I would be excited to hear your feedback?

[k06a]

This change was proposed to both original libraries containing Solidity RLP decoders:
hamdiallam/Solidity-RLP#2 (already merged)
androlo/standard-contracts#9 (not yet merged)

We in multitoken.io (multitoken.com) are working on decentralized bridges between blockchains and watching over related projects. Nice framework!

[Shirikatsu]

Thanks @k06a!

The code looks good however I'm currently investigating where (and why) some of our tests are failing and it's currently boiling down to some error in this function from a brief look.