Started port to upstream VIM

[pheiduck]

Hey @wavded,

I started to Port this Plugin to upstream VIM
vim/vim#14656
Please take a Review if you can and help to improve. I pinged all Maintainers which are included here.

Best regards,
Philip Heiduck

[wavded]

Sounds great, it's been years since I've seriously looked at this plugin. Think the community would benefit from an official upstream VIM version.