Core: Modernize

modernize-use-auto
modernize-use-nullptr
modernize-use-override
modernize-use-using
modernize-use-default-member-init (partially)

Change-Id: Idf10d7ffb1d98a04edc09a25c35e4e9e3abe87b5
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/coreplugin.cpp

@@ -70,9 +70,6 @@ using namespace Core::Internal;
 using namespace Utils;
 
 CorePlugin::CorePlugin()
-  : m_mainWindow(nullptr)
-  , m_editMode(nullptr)
-  , m_locator(nullptr)
 {
     qRegisterMetaType<Id>();
     qRegisterMetaType<Core::Search::TextPosition>();