Allow message to be multiline

[f0s3]

I want my login screen to have this:

Hello
world
Password:

And I could not achieve this for two reasons:

• Trying -p "Hello\nworld" doesn't add newline char
• There is an empty newline between world and Password: which I couldn't remove

[xyb3rt]

-p "Hello
world"

should fix point one. The newline addressed in point two is intentional, because the message is not part of the password prompt.