fix the q mapping again
fix the q mapping again

since we are now ":edit"ing a new buffer for secondary nerd trees, we
have to store the previous buffer number otherwise we get into an
infinite loop because we go back to a directory buffer which causes
another secondary nerd tree to open etc

nywilken/dotfiles,tschundler/dotfiles,iff/dotfiles-old,nywilken/dotfiles,tschundler/dotfiles,iff/dotfiles-old,tschundler/dotfiles