Support exporting a wallet

[sdankel]

Hi @kayagokalp

The enhancement to import 12 world mnemonic seems to work in the package.

the export package is what seems to be missing. I am taking it up. If possible please assign the issue.

rasied a PR for the same #227

Originally posted by @adirola in #222

[adirola]

Hey @sdankel would be great if you could assign me the issue, as the base code is already written will do the required modification.

[sdankel]

@adirola Done! When you rebase on master, you'll have to make some adjustments. There were some changes after upgrading dependencies that you'll see.