Clang: implement current document filter

Filter is based on full token infos which come
from clang code model after token infos with pure
highlighting information.

Inprovements:
- functions also provide the return type after the signature
- now supports Q_PROPERTY
- all c++ features that clang 5.0 supports

Change-Id: If3e30d238984f39df8d2c3b9ba3ee085c4117f3d
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangcodemodel/clangmodelmanagersupport.cpp

@@ -89,6 +89,9 @@ ModelManagerSupportClang::ModelManagerSupportClang()
     else
         m_followSymbol.reset(new CppTools::FollowSymbolUnderCursor);
 
+    CppTools::CppModelManager::instance()->setCurrentDocumentFilter(
+                std::make_unique<ClangCurrentDocumentFilter>());
+
     Core::EditorManager *editorManager = Core::EditorManager::instance();
     connect(editorManager, &Core::EditorManager::editorOpened,
             this, &ModelManagerSupportClang::onEditorOpened);