Provide ability to configure 'show summary in full view' node setting

When adding or editing a node, it is possible to enable or disable a checkbox "show summary in full view". This determines whether the teaser entered is displayed on the full node page and defaults to true. I have a content type in my source CMS where this should be set to false.

The attached patch adds a new field to the node content set configuration form, and also inserts the necessary at the start of the node body when the option is disabled, so as to avoid editing problems later.

Cheers,
Stella