GitLab

Modify directory listing aliases to make more sense. Remove conflicting helper
function (mcd conflicts with mtools).

Also an alias for the function.

The ll alias is a very common default for bash in Linux distributions, so use
that definition.

Initial implementation of a new plugin system, so that people can managed which aliases/functions they want.

Moving all zsh config options into a lib/ subdirectory to make way for some upcoming changes to directory structure and configuration options