now that rtyaml is in pypi, remove its source here and add it to requirements.txt

Also reverting the recent change for preserving initial comment blocks (not committed to the version in pypi) in
ddb73d42bdfba1c2e7d74387ca43a1f91d7922c4, 31f5c2e685fe9414404b55d8a06008d9b4ba370b, and e81a592b6108c22612062c0f20da9ec492de7ab8
And instead of those changes, just copy the initial comment block data over when writing the social media file.