External dependencies:
  Emacs:
    optional:
      `private.el` in loadpath
  Zsh:
    optional:
      `$LOCALDIR/pre` - will be loaded before most of zsh config.
      `$LOCALDIR/post` - will be loaded after zsh config.

make [refresh] : Update byte-compiled Emacs files.
make compile   : Compile all Emacs files.
make deploy    : Deploy all files (using symbolic links).
make all       : compile and deploy.