C++: add code-model settings to choose one by mime-type.

The model-manager now supports multiple code models for semantic
highlighting and code completion, and will choose one based on the
mime-type of the editor.

The settings page is currently disabled. It will get enabled when a
second plug-in lands that has a ModelManagerSupport class.

Change-Id: I10023f52322ed6860397da15dba1c231e80e6517
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/cpptools/cpptoolsplugin.h

@@ -49,6 +49,7 @@ namespace Internal {
 
 class CppModelManager;
 struct CppFileSettings;
+class CppCodeModelSettings;
 
 class CPPTOOLS_EXPORT CppToolsPlugin : public ExtensionSystem::IPlugin
 {
@@ -68,6 +69,8 @@ public:
     void extensionsInitialized();
     ShutdownFlag aboutToShutdown();
 
+    QSharedPointer<CppCodeModelSettings> codeModelSettings() const;
+
 public slots:
     void switchHeaderSource();
     void switchHeaderSourceInNextSplit();
@@ -225,6 +228,7 @@ private:
 
 private:
     QSharedPointer<CppFileSettings> m_fileSettings;
+    QSharedPointer<CppCodeModelSettings> m_codeModelSettings;
     CppToolsSettings *m_settings;
 };