Really, there is no reason to use zsh when fish exists, at least not for
my use case. Maintaining one set of shell config files is easier than
two, so I'm removing the zsh files.
Some other changes in this commit include:
- The addition of the current user and hostname to the fish prompt
- The addition of some zsh functions I re-implemented in fish
- The removal of the dircolors file (not needed with exa anyway)
- The removal of some aliases I never used
-