Debugger: Use the code model to detect unitialized variables.

This should save debugger round trips and crashes in the debugging
helpers.
Add respective option to debugging helper option page, defaulting to
true.On this occasion, make CDB detect shadowed variables correctly
and display them as "<shadowed n>" as does the Gdb engine by
reversing the direction in which
CdbSymbolGroupContext::populateINameIndexMap works.
Rubber-stamped-by: hjk <qtc-committer@nokia.com>

src/plugins/debugger/debuggermanager.h

@@ -59,6 +59,10 @@ namespace TextEditor {
 class ITextEditor;
 }
 
+namespace CPlusPlus {
+    class Snapshot;
+}
+
 namespace Debugger {
 namespace Internal {
 
@@ -180,6 +184,8 @@ public:
                                  QString *settingsCategory = 0,
                                  QString *settingsPage = 0) const;
 
+    const CPlusPlus::Snapshot &cppCodeModelSnapshot() const;
+
     static DebuggerManager *instance();
 
 public slots:
@@ -232,6 +238,7 @@ public slots:
     void setRegisterValue(int nr, const QString &value);
 
     void showStatusMessage(const QString &msg, int timeout = -1); // -1 forever
+    void clearCppCodeModelSnapshot();
 
 public slots: // FIXME
     void showDebuggerOutput(const QString &msg)
@@ -267,7 +274,8 @@ private:
     Internal::ThreadsHandler *threadsHandler() const;
     Internal::WatchHandler *watchHandler() const;
     Internal::SourceFilesWindow *sourceFileWindow() const;
-    QWidget *threadsWindow() const;    
+    QWidget *threadsWindow() const;        
+
     Internal::DebuggerManagerActions debuggerManagerActions() const;
 
     void notifyInferiorStopped();