Debugger: Make tooltips pinnable.

Replace old debugger tooltip by a new ToolTipManager which
has a list of AbstractDebuggerToolTipWidget with the functionality
to 'acquire' an engine (display its data) and 'release' it
(store engine data and display them as 'previous') and serialization
to XML session data.
DebuggerTreeViewToolTipWidget implements AbstractDebuggerToolTipWidget
for tree model acting as  a filter on watch models.

Rubber-stamped-by: hjk

src/plugins/debugger/cdb/cdbengine.h

@@ -85,7 +85,8 @@ public:
     virtual ~CdbEngine();
     // Factory function that returns 0 if the debug engine library cannot be found.
 
-    virtual void setToolTipExpression(const QPoint &mousePos, TextEditor::ITextEditor *editor, int cursorPos);
+    virtual void setToolTipExpression(const QPoint &mousePos, TextEditor::ITextEditor *editor,
+                                      const DebuggerToolTipContext &ctx);
     virtual void setupEngine();
     virtual void setupInferior();
     virtual void runEngine();
@@ -215,7 +216,7 @@ private:
 
     QString normalizeFileName(const QString &f);
     void updateLocalVariable(const QByteArray &iname);
-    void updateLocals();
+    void updateLocals(bool forNewStackFrame = false);
     int elapsedLogTime() const;
     void addLocalsOptions(ByteArrayInputStream &s) const;
     unsigned parseStackTrace(const GdbMi &data, bool sourceStepInto);