Create Wallet example project

[msafi]

I'm not sure if everything in the roadmap is still relevant, but there were plans to create a wallet example project. I'm interested in working on that because of a couple of reasons:

1. It's an opportunity for me to learn how to use bitcoinjs-lib and how to build a bitcoin wallet
2. I plan to use this wallet in production as part of another project

I started the work here: orange-org/bitcoinjs-wallet#1

(If there's no interest anymore in this effort, feel free to close this issue.)

The project I created uses TypeScript and Prettier but otherwise has a slightly different setup from the libraries in the bitcoinjs org. For example, it uses ESLint instead of TSLint and it uses Jest instead of Mocha. I think these choices are more modern, but I can change them if you want. When the work on that repo is finished, we can transfer it to the bitcoinjs org.

With regard to the API of the wallet library itself, the way I'm going about it is by asking myself the following question:

If I were building an Electrum clone, which wallet APIs would be best to have

I have posted more questions and thoughts on the PR orange-org/bitcoinjs-wallet#1

[Overtorment]

there are a lot of wallets that use bitcoinjs-lib:

but yeah, weeks of coding can save you hours of planning