Tab or window option in always private browsing mode

Switching from Window.localStorage to browser.storage.local in order to have the setting persisted.

Storage permission fix

Fixed storage permission in order to persist the option to display the scan results in a new tab instead of a new window.

Display results in new window or new tab

Added preferences pane with the configuration option.

Queued scans enablement

Deal with queued scans.
Enable l18n.
Use fetch instead of XMLHttpRequest.