Separate scope in classes quickopen filter

The scope of the classes is now separated and displayed in the second
column, and not included in the search.

src/libs/cplusplus/Icons.h

@@ -47,7 +47,7 @@ class CPLUSPLUS_EXPORT Icons
 public:
     Icons();
 
-    QIcon iconForSymbol(Symbol *symbol) const;
+    QIcon iconForSymbol(const Symbol *symbol) const;
 
     QIcon keywordIcon() const;
     QIcon macroIcon() const;