Generate a beancount file with transaction history for a descriptor

[nochiel]

This PR builds on #55.

Given an output descriptor, we would like to:

• Generate addresses derived from that descriptor up to some gap size.
• Obtain a transaction history for the generated addresses.
• Output a beancount report file with transaction ('trading') history. The beancount transactions should have fiat amounts for the bitcoin transactions at the exchange rate at the time the transaction was made.

TODO (In subsequent PRs after this is merged)

• Blockchain Commons and @ChristopherA should confirm what additional accounting data should be in the beancount file.

• Tests for each descriptor type. Ensure that Spotbit can generate valid addresses supported by BDK.

  • Ensure that Spotbit can generate addresses from descriptors used by Bitcoin Core.

• UI: Add beancount UX to web front-end.

• Package spotbit as an executable.

Example:

python app.py beancount "wpkh(tpubD9hudZxy8Uj3453QrsEbr8KiyXTYC5ExHjJ5sNDVW7yKJ8wc7acKQcpdbvZX6dFerHK6MfVvs78VvGfotjN28yC4ij6nr4uSVhX2qorUV8V/0/*)"

Outputs: spotbit.beancount

2008-10-31 commodity BTC
name: "Bitcoin"
asset-class: "cryptocurrency"
2018-04-02 open Assets:BTC	BTC
2018-04-02 open Liabilities:Cash:USDT	USDT
2018-04-02 * "tb1qcrekknrspx28t9vl53ltsag5gqgqdj066ydf75" "Transaction hash: 2a2f7f24761fa54cb6e559efea5678415d9cbbabc42e6a4e2ce463ee3c446230"
Assets:BTC 1.00000000 BTC { 6935.16 USDT }
Liabilities:Cash:USDT	- 6935.16 USDT 2018-04-02 * "tb1q45whzx3emntntnpzjdx3gzj6z5cgxakkg7s3sa" "Transaction hash: 387123efcaa707759a4af8159cb1309fae86b793d26b5fd8bba42637852dde89"
Assets:BTC	- 0.36300616 BTC @ 6935.16 USDT Liabilities:Cash:USDT 2517.51 USDT 2018-04-02 * "tb1qgv5484m83e2mzz3n8tf4snvnwj5qgqgampnhvv" "Transaction hash: 387123efcaa707759a4af8159cb1309fae86b793d26b5fd8bba42637852dde89"
Assets:BTC	- 0.63699243 BTC @ 6935.16 USDT Liabilities:Cash:USDT 4417.64 USDT 2018-04-02 * "tb1q45whzx3emntntnpzjdx3gzj6z5cgxakkg7s3sa" "Transaction hash: 387123efcaa707759a4af8159cb1309fae86b793d26b5fd8bba42637852dde89"
Assets:BTC 0.36300616 BTC { 6935.16 USDT }
Liabilities:Cash:USDT	- 2517.51 USDT 

References

• Output descriptors:
  • https://bitcoindevkit.org/descriptors/
  • https://outputdescriptors.org/
• https://beancount.github.io/docs/trading_with_beancount.html

[nochiel]

@icculp If you have time, here's another PR that could benefit from your review. 😄

[ChristopherA]

@nochiel Ready for merge?

[nochiel]

@nochiel Ready for merge?

Yes, it is. Thanks. 👍🏾

[ChristopherA]

This PR was reviewed by an external volunteer, @hanhungsoo. As this project is still technically still "Late Alpha" and the current online version is unstable, I am going ahead and committing this PR to the master branch without additional review.

@shannona — we should tag this commit.