Debugger: Fix Symbian.

...which subclasses DebuggerRunner and does not call
DebuggerPlugin::startDebugger(), which connects the
engine, leading to strange malfunctions. Move functionality
to DebuggerRunner::start() to make it self-contained.
Add object names to engines for easier debugging.

Reviewed-by: hjk

src/plugins/debugger/qml/qmlengine.cpp

@@ -106,7 +106,7 @@ QmlEngine::QmlEngine(const DebuggerStartParameters &startParameters)
     , m_adapter(new QmlAdapter(this))
     , m_addedAdapterToObjectPool(false)
 {
-
+    setObjectName(QLatin1String("QmlEngine"));
 }
 
 QmlEngine::~QmlEngine()