Fix package loading in lang/ess
Fix package loading in lang/ess

Originally `load-ess-on-demand` used `use-package` for the purposes of
actually loading `ess-site` and related elisp for dealing with R. But
since `use-package` doesn't return true or false when a package is
actually successfully loaded anymore, and the semantics of how it will
work aren't precisely clear, it makes sense to use `require` here
instead.

    (defun load-ess-on-demand ()
      (interactive)
      (-all? '---truthy? (list
                          (require 'ess-site)
                          (require 'ess-R-object-popup)
                          (require 'ess-R-data-view))))

All the normal hooks setup by `use-package` will work as normal. I
actually don't see a reason we should use `use-package` instead of
`require` in this specific instance. Since `use-package` often defers
loading packages, it's arguably clearer to use `require` in this
particular instance.

tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs