Change Details

Per @legoktm: * AbortMove has been removed completely. * MovePageIsValidMove should only be used for technical restrictions. NS_TOPIC qualifies here. * However, for permissions issues (is the destination namespace Flow and if not do they have flow-create-board), we should use MovePageCheckPermissions. While we're at this, document these hooks on-wiki (it's currently only in docs/hooks.txt)