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.h

@@ -137,7 +137,7 @@ public:
     CToolBoxMacro* GetMacro(int iIndex, bool bToolbox);
     //! Get the index of a macro from its title.
     int GetMacroIndex(const QString& title, bool bToolbox) const;
-    //! Creates a new macro in the manager. If the title is duplicate, this returns NULL.
+    //! Creates a new macro in the manager. If the title is duplicate, this returns nullptr.
     CToolBoxMacro* NewMacro(const QString& title, bool bToolbox, int* newIdx);
     //! Try to change the title of a macro. If the title is duplicate, the change is aborted and this returns false.
     bool SetMacroTitle(int index, const QString& title, bool bToolbox);