Replace ag.vim with vim-grepper
Replace ag.vim with vim-grepper

ag.vim seems to have an artefact, which doesn't occur with vim-grepper.
It does function well with neovim async. I like the idea of a generic
tool, and it does function well. I didn't like Ack.vim, because it
didn't work properly when no results were found.

paretje/dotfiles,paretje/dotfiles,paretje/dotfiles,paretje/dotfiles,paretje/dotfiles