Debugger: Add infrastructure for message tracepoints.

Add context menu to add a 'message tracepoint', that is,
a trace point that outputs a user message and continues.
Intended to be a replacement for manually inserting
a qDebug() into the code to understand the call sequence.
Yet to be implemented for gdb.

Change-Id: I1c303001421fbbae74d98d15d52718579350db6e
Rubber-stamped-by: hjk
Reviewed-on: http://codereview.qt.nokia.com/756
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/debugger/debuggerstreamops.cpp

@@ -191,6 +191,7 @@ QDataStream &operator<<(QDataStream &stream, const BreakpointParameters &s)
     stream << s.tracepoint;
     stream << s.module;
     stream << s.command;
+    stream << s.message;
     return stream;
 }
 
@@ -210,6 +211,7 @@ QDataStream &operator>>(QDataStream &stream, BreakpointParameters &s)
     stream >> b; s.tracepoint = b;
     stream >> str ; s.module = str;
     stream >> str ; s.command = str;
+    stream >> str ; s.message = str;
     return stream;
 }