CreateDebtRequestDialog: Fix issue with divide button getting into bad state

Surprisingly difficult to tell the difference between a user invoked
button click/entry change and programmatic change. Block the clicked
signal while we're resetting the divide button state to avoid re-entrancy
with the clicked signal.

v2: Change Optional unwrap to more idiomatic Rust way.

Adds a divide by two button to CreateDebtRequestDialog

Adds a divide by two button next to the "amount" field, and implements
some special behavior for when the button resets or when the field changes.

Move state restoration logic for the debt requests model inside the block that creates it

Fix compiler warnings

More state restoration work

Remember window settings

Fix copy behavior in details view

Fix error message that occasionally appears when loading the blockchain from nothing.

Update iOS signing details

cli: Adds `nonce` and `show` commands

More robust tracking of nonce values

Fix bug where switching wallets doesn't correctly update UI

Fix crash when error dialogs appear

Fix cryptic build error

cli: Adds the ability to create debt requests. Also documents contract controller.

Adds multiple window (scene) support

Fix warnings

DebtRequestDetailViewController: Fixes bug where footer buttons are laid out incorrectly

Implements the ability to reject debt requests

GTK: Implements rejected state display

TODO: Should add a reject button/reject functionality as well