Editor code: tidy up BOOLs,NULLs and overrides pt2.

A few 'typedefs' replaced by 'using's
This shouldn't have any functional changes at all, just c++17 modernization
It's a part 2 of a split #2847

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

Code/Editor/Lib/Tests/test_EditorUtils.cpp

@@ -23,12 +23,12 @@ namespace EditorUtilsTest
             BusConnect();
         }
 
-        ~WarningDetector()
+        ~WarningDetector() override
         {
             BusDisconnect();
         }
 
-        virtual bool OnWarning(const char* /*window*/, const char* /*message*/) override 
+        bool OnWarning(const char* /*window*/, const char* /*message*/) override 
         {
             m_gotWarning = true;
             return true;