Add more ways to find bib files

[mikebarkmin]

Maybe we can use the algorithm of vim-pandoc for searching bib files. https://github.com/vim-pandoc/vim-pandoc/blob/0d4b68eb7f63e43f963a119d60a3e29c2bb822e0/python3/vim_pandoc/bib/collator.py#L18

This would make this plugin very versatile.

[sbock17]

Has anyone found a solution for this?

[jc-doyle]

Sorry haven't really given this plugin any love, wrote this when I was writing a dissertation and haven't had much time recently. I initially thought of using plenary.nvim.

Either implementation wouldn't take that much effort to get going, and can look to implement this when I find the time. Very open to PR's