imported old super_admin mod
enabled super_admin mod in crabgrass.development.yml
super_admin: moved routes to config/routes
recovered "sites" initializer from old crabgrass repository
enabled site "site1" in development config, to be able to work with superadmin
added Crabgrass.mod_routes to add routes from mods before the catchall route
superadmin: use Crabgrass.mod_routes instead of regular plugin routes
superadmin: removed cache sweepers
superadmin: added missing helpers
added simple 'admin' layout
superadmin: removed on(Site.current) from UsersController#index - it doesn't exist anymore
superadmin: fixed nav template
superadmin: re-added 'become' route
superadmin: various view fixes
fix alphabetized group list sql
adding admin theme with admin toplevel menu

Still lacking the submenus. Only active right now if you add ?theme=admin in dev mode or activate the theme in the configuration
added initial admin dropdown menu

it's based on the theme menu structure so we can easily extend it from other admin mods