Switch to one-time subaddresses, remove primary address

[woodser]

Currently, the design shows the ability to deposit to the wallet's primary address.

Instead, the application should only use one-time subaddresses. The user can generate a new subaddress when depositing funds to the wallet or to make or take an offer.

The primary address should be removed throughout the application, except possibly shown in settings like with the mnemonic phrase.

In addition, the QR code should display by default, so the user does not need to click a button to show the QR code.