Editor code: tidy up BOOLs,NULLs and overrides pt5. (#2876)

A few 'typedefs' replaced by 'using's
This shouldn't have any functional changes at all, just c++17 modernization
It's a part 5 of a split #2847

Signed-off-by: Nemerle <nemerle5+git@gmail.com>

Co-authored-by: Nemerle <nemerle5+git@gmail.com>

Code/Editor/LayoutWnd.cpp

@@ -98,7 +98,7 @@ CLayoutWnd::CLayoutWnd(QSettings* settings, QWidget* parent)
     , m_settings(settings)
 {
     m_bMaximized = false;
-    m_maximizedView = 0;
+    m_maximizedView = nullptr;
     m_layout = (EViewLayout) - 1;
 
     m_maximizedViewId = 0;
@@ -729,7 +729,7 @@ void CLayoutWnd::OnDestroy()
     if (m_maximizedView)
     {
         delete m_maximizedView;
-        m_maximizedView = 0;
+        m_maximizedView = nullptr;
     }
 }