Editor code: tidy up BOOLs,NULLs and overrides pt6.

A few 'typedefs' replaced by 'using's
This shouldn't have any functional changes at all, just c++17 modernization
It's a part 6 of a split #2847

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

Code/Editor/ToolBox.cpp

@@ -186,7 +186,7 @@ const CToolBoxMacro* CToolBoxManager::GetMacro(int iIndex, bool bToolbox) const
         assert(0 <= iIndex && iIndex < m_shelveMacros.size());
         return m_shelveMacros[iIndex];
     }
-    return NULL;
+    return nullptr;
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -202,7 +202,7 @@ CToolBoxMacro* CToolBoxManager::GetMacro(int iIndex, bool bToolbox)
         assert(0 <= iIndex && iIndex < m_shelveMacros.size());
         return m_shelveMacros[iIndex];
     }
-    return NULL;
+    return nullptr;
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -240,14 +240,14 @@ CToolBoxMacro* CToolBoxManager::NewMacro(const QString& title, bool bToolbox, in
         const int macroCount = m_macros.size();
         if (macroCount > ID_TOOL_LAST - ID_TOOL_FIRST + 1)
         {
-            return NULL;
+            return nullptr;
         }
 
         for (size_t i = 0; i < macroCount; ++i)
         {
             if (QString::compare(m_macros[i]->GetTitle(), title, Qt::CaseInsensitive) == 0)
             {
-                return NULL;
+                return nullptr;
             }
         }
 
@@ -264,7 +264,7 @@ CToolBoxMacro* CToolBoxManager::NewMacro(const QString& title, bool bToolbox, in
         const int shelveMacroCount = m_shelveMacros.size();
         if (shelveMacroCount > ID_TOOL_SHELVE_LAST - ID_TOOL_SHELVE_FIRST + 1)
         {
-            return NULL;
+            return nullptr;
         }
 
         CToolBoxMacro* pNewTool = new CToolBoxMacro(title);
@@ -275,7 +275,7 @@ CToolBoxMacro* CToolBoxManager::NewMacro(const QString& title, bool bToolbox, in
         m_shelveMacros.push_back(pNewTool);
         return pNewTool;
     }
-    return NULL;
+    return nullptr;
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -333,7 +333,7 @@ void CToolBoxManager::Load([[maybe_unused]] ActionManager* actionManager)
 void CToolBoxManager::Load(QString xmlpath, AmazonToolbar* pToolbar, bool bToolbox, ActionManager* actionManager)
 {
     XmlNodeRef toolBoxNode = XmlHelpers::LoadXmlFromFile(xmlpath.toUtf8().data());
-    if (toolBoxNode == NULL)
+    if (toolBoxNode == nullptr)
     {
         return;
     }