EZP-21149: improve input validation for createContentType() and addFieldDefinition()
EZP-21149: fix mistakes exposed by improved input validation
EZP-21149: removed deprecated todo
Reused functionality available in DomainMapper and removed duplicated code
PHPDoc: typos
Fixed: indentation
Fixed: identifier is required in ContentTypeCreate
Merge pull request #517 from ezsystems/fix-EZP-21149-contenttype-names-required

Fix EZP-21149: Fatal error when creating content type without "names" attribute