[Enhancement] Markdown Preview Support

[snoweuph]

It would be awesome to have support for "mrjones2014/mdpreview.nvim"
I would love to see this with some simple Prompt Option:

opt = { mdpreview = true}

I would expect this to pass the display output through the stuff the

require('mdpreview').preview()

Function normal does, so the users settings for that plugin work.

It already has an API

I also expect this to only work together with the displaying enabled,
and it would need compatibility for splitting and co. too.
It should be disabled by default, and be an optional feature.

I might see, if I find the Time to do this myself, but the hope for that isn't that great