Squashed 'modules/base/inline_entity_form/' content from commit 8229859

git-subtree-dir: modules/base/inline_entity_form
git-subtree-split: 8229859b9c8f2bcf58fa683cd29b3b79243de290
New: Add modules/base/inline_entity_form.
Merge commit 'c426e3d8d8aa7f0c95131b3ab43ee2d37f789df4' as 'modules/base/inline_entity_form'