Replace all occurrences of [ with [[ in bash and zsh scripts and
configs.
Performance wise it makes sense to use the builtin instead of calling an
external command also when from a functionality stand point `test` would
suffice.
Autoload the function instead of declaring it directly.
Add functionality for multiple targets. It should now pretty much
perform like `command ls`.
Refactored code to use more zsh extensions like globbing instead of
parsing the output of `ls` making it a lot faster.
