Add builtin types for 8 and 16bit integers, as well as unsigned 32bit

Warning: main.qml:12:42: Type "quint16" of property "count" not found. This is likely due to a missing dependency entry or a type not being exposed declaratively.
    readonly property int count: Message.count
                                         ^^^^^
Warning: main.qml:12:42: Could not compile binding for count: Cannot load property count from Message of Message.
    readonly property int count: Message.count
                                         ^^^^^
Warning: main.qml:18:40: Property "arg" not found on type "void"
            text: qsTr('Messages: %1').arg(win.count)
                                       ^^^
Warning: main.qml:18:40: Could not compile binding for text: Type QJSPrimitiveValue of void does not have a property arg for calling
            text: qsTr('Messages: %1').arg(win.count)
                                       ^^^

qrc:/msg/main.qml:22:13: Unable to assign [undefined] to QString