Important: #70956 - Behavior of Page TSconfig options keepItems, addItems and removeItems changed

See forge#70956

Description

The behavior of Page TSconfig options keepItems, addItems and removeItems has been restored to state of TYPO3 CMS 6.2-7.4 and the execution order of these options has been formalized.

The first option to be evaluated is keepItems, followed in turn by addItems and removeItems. All three options are evaluated after items have been added to the configuration by sources like folders or foreign tables.