Some small issues

[hrxi]

• Passphrase input on my machine doesn't let me focus any other window, e.g. my password manager.
• Maybe manual entropy input could be removed as it's confusing me and other users.
• Attestation info should include an explicit disclaimer that this is used for this procedure, otherwise people might be social engineered into posting random bytes.
• After entering the passphrase, contribute shows the confusing message "Contributing! Please unmount and remove the USB drive containing your keys now."

[hrxi]

• Don't override nimiq.keys if you're running the generate binary twice.