Review core data structures in Stellar.

[debnil]

Reviewing the core data structures in the Stellar protocol will help guide an understanding of the functions needed in the CLI tool. It's also important to compare these with the data structures used in other blockchains, like unspent transactions, because that will help understand the differences between this CLI tool and the existing ones.

Useful links include:

• the Horizon API (here)
• the developer guide (here)
• the accounts model (here)
• comparison between utxos and accounts (here)