This is a preparation to start experimenting with zsh. The idea is to
share the aliases and environment setup between both shells to avoid
having a bunch of duplication. Even if I decide to stick with zsh it
would be nice to keep the bash configs around for systems where I might
not want to install zsh for some reason. We'll see how this goes...
I was previously using relative paths to $PWD with the implicit
assumption that I would always run `bootstrap` from the dotfiles
root directory. This commit fixes that.
The links are only removed if they are broken and the target was within
the dotfiles bin directory. This makes it easier to deal with removed
and renamed scripts so I don't have to go hunt for them by hand.
