API Remove DataObject::validateModelDefinitions, and move to DataObjectSchema
API Remove deprecated 3.0 syntax for addSelect()
API made DataList::createDataObject public
API Move component parsing logic to DataObjectSchema
API Remove support for triangular has_many / belongs_many relationships
API extension hook "getIsModifiedOnStage" renamed to "updateIsModifiedOnStage", also moved "getIsDeletedFromStage", "getIsModifiedOnStage" and "getIsAddedToStage" from SiteTree class to Versioned data extension class