C++ editor: support nested class of enclosing template

Fixing:
* highlighting
* tooltips
* find usage
* selecting

Task-number: QTCREATORBUG-8245
Change-Id: I6e900799e43126706125b7e424567fca2b2c223e
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/libs/cplusplus/FindUsages.cpp

@@ -260,6 +260,8 @@ void FindUsages::checkExpression(unsigned startToken, unsigned endToken, Scope *
     if (! scope)
         scope = _currentScope;
 
+    // make possible to instantiate templates
+    typeofExpression.setExpandTemplates(true);
     const QList<LookupItem> results = typeofExpression(expression, scope, TypeOfExpression::Preprocess);
     reportResult(endToken, results);
 }