Debugging PHP with Vim
Status: I have not gotten this to work.
https://github.com/vim-vdebug/vdebug
https://juampynr.github.io/vim-drupal8/#/11
https://www.mediacurrent.com/blog/debug-drupal-php-vim-vdebug/
http://docs.drupalvm.com/en/latest/extras/xdebug/
https://addons.mozilla.org/en-US/firefox/addon/xdebug-helper-for-firefox/
https://stackoverflow.com/questions/31778944/commands-that-work-in-vim-dont-work-in-vimrc#31779789