QmlProfiler: Add a QmlTypedEvent and extend QmlEvent

The QmlTypedEvent is mainly useful to read a generic QmlEvent and
QmlEventType from a QPacket. QmlEventType has a stream operator to do
exactly that. QmlEvent also gets further options to store 32-bit data
in addition to 64- and 8-bit data. Also, with the more generic storage
layout we can reduce the memory consumption of range events by 50%.
This comes at the cost of additional memory allocations for non-range
events, but as non-range events are significantly less frequent than
range events, this is a good tradeoff. Finally the new storage layout
lends itself to efficient serialization, which will help when
developing new storage and transfer formats for QML traces.

Change-Id: I420de68b0142f23c8fb2ca8b329d7ffe69c83fe0
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

src/plugins/qmlprofiler/debugmessagesmodel.cpp

@@ -113,7 +113,7 @@ void DebugMessagesModel::loadData()
             continue;
 
         m_data.insert(insert(event.timestamp(), 0, type.detailType),
-                      MessageData(event.stringData(), event.typeIndex()));
+                      MessageData(event.string(), event.typeIndex()));
         if (type.detailType > m_maximumMsgType)
             m_maximumMsgType = event.typeIndex();
         updateProgress(count(), simpleModel->events().count());