Support piping output into nvim from terminal

[samjwill]

Doing so should unnest a buffer containing the piped text.

e.g.) cat my_file.txt | sed 's/sun/moon/' | nvim

[Lazerbeak12345]

perhaps providing https://github.com/lucc/nvimpager integration would be the best way to do this. paired, as is, they almost work, but nvimpager seems to still be sending control chars & etc. for colorizing.