Same motivation as in https://github.com/NixOS/nixpkgs/pull/28378. zsh.initExtra parameter can be used by external modules which can redefine user aliases. This change will give user-defined aliases the highest priority.
To pass compinit security checks, plugins are liked into ~/zsh/plugins folder. This also solves issues with a slow start up, see https://github.com/rycee/home-manager/pull/56#issuecomment-328057513.
This new module adds a "news" feature to Home Manager. See #52. Many thanks to @nonsequitur and @uvNikita for suggestions and improvements.
