RTMP Buffer / Delay add

Hey there,

Would love to add a new feature - the ability to add a significant delay (say 5-15mins).

OBS/Xsplit do this by saving to ram before streaming - https://github.com/jp9000/obs-studio/commit/05388655531026e3421690296c17ac004265c0db

probably a very difficult thing to do but for us this is critical

Thanks!