[ENG] Global Smart Fields

Global Smart Fields have the same functionality as regular Smart Fields except that they are available in all templates, rather than just in 1 template. This allows owners to define Smart Fields that are relevant for any type of template at once, rather than having to re-create these fields for every template.

Global Smart Fields can only be created, changed and deleted by Owners. This is, because Global Smart Fields, when created, appear in every template and when removed may therefore affect any template. Editors of a Template can use Global Smart Fields, however, they can't edit or change them. For users editing documents, Global Smart Fields work like any other type of Smart Field.