BSIP82: Add ed25519-sha-256 Support for HTLC

Today banks are deploying solutions for Cross-Currency Settlement and FX Market Making.

When those solutions are ILP-enabled, banks won’t have to change much – market makers will still hold accounts at their banks and they’ll establish relationships with the other banks and market makers with whom they want to transact. ILP enables transactions across any number of different ledgers and exchanges using cryptographic escrow and a specialized two-phase commit protocol.

BitShares is aiming to become the best bridge of assets for market makers providing cross-currency liquidity as a software to individuals and corporate, supporting the ed25519-sha-256 pre-image hashing algorithm would enable BitShares to become compatible with the financial system transmission and future.

[Interledger crypto-conditions implemented in C, including simple JSON api](https://github.com/ssadler/libcryptoconditions)
[JS code for creating the Condition & Fulfillment on interledger](https://github.com/ioBanker/codes/blob/master/escrow.js)

The issue names no BitShares files, tests, or entry points. Start by reviewing the linked libcryptoconditions C implementation and JS escrow example to determine the required HTLC condition and fulfillment behavior; define a concrete acceptance test for ed25519-sha-256 support before implementation.

Written by the indexing model from the issue text.