Flag for "line" input/output for shell-centric use cases

[philrz]

At the time this issue is being opened, super is at commit 9830034.

Community user @chrismo suggested in a public Slack thread:

I feel like it'd be nice to have a shortcut for super -i line -f line — 'twould make it slightly handier for text manipulation when i'd rather use super than awk/sed/etc ... i suppose i could alias something in my shell 🤔