@ core/db/models/conversation.php: improved
@ core/db/models/item.php
@ core/db/models/abstractModel.php

const { NOOP | FLAG_SET | FLAG_UNSET | WHATEVER } moved from {core/db/models/item.php} to {core/db/models/abstractModel.php}
@ core/db/models/conversation.php: improved in @::countAll()
@ modules/defaultModule/views/layout/genLayoutHeader.php: unread conversation notification now is in effect due to commit@3870e97
@ modules/opsModule/models/renderConversation.php: a UI fix