Wrappers, helpers, and syntactic sugar on BDK discussion

[thunderbiscuit]

No description provided.

[thunderbiscuit]

To move the discussion forward on this, I have started a "sugar" library that would work on bdk-android and bdk-jvm. The repo is here.

At the moment it does 2 things but I'd love to add more.

1. Adding a .sat and .btc values on the common Int, Long, Float, Double units to provide simple checks for values and allow to express them in either satoshis or bitcoin, while inlining the actual ULong value.
2. Adding an infix function called before that allows comparison between two transactions and returns a boolean.

Examples:

// example 1
TxBuilder()
    .addRecipient(Address(faucetAddress).scriptPubkey(), 1000.sat)
    .feeRate(1.2f)
    .finish(wallet)

TxBuilder()
    .addRecipient(Address(faucetAddress).scriptPubkey(), 0.004.btc)
    .feeRate(1.2f)
    .finish(wallet)

// example 2
val txList = wallet.listTransactions()
val tx1: TransactionDetails = txList[0]
val tx2: TransactionDetails = txList[1]

if (tx1 before tx2) {
    println("tx1 is older than tx2")
}

[thunderbiscuit]

Closing this issue to combine the discussion with #266.