Consider owner configuration when adding a new line

[jonatas]

When adding a new line / pattern, we need to define the owner. If we already configured it, we could adopt the configuration instead of re-type it.

We could say:

File owner (leave empty to use <configured-owner>):

Or we could say:

New line: pattern @default_owner

With line editing from: https://github.com/piotrmurach/tty-reader