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/Plugins/ProjectSettingsTool/PlatformSettings_Android.cpp

@@ -165,8 +165,8 @@ namespace ProjectSettingsTool
             if (editContext)
             {
                 editContext->Class<AndroidSplashscreens>("Splashscreens", "All splashscreen overrides for Android.")
-                    ->DataElement(0, &AndroidSplashscreens::m_landscapeSplashscreens)
-                    ->DataElement(0, &AndroidSplashscreens::m_portraitSplashscreens)
+                    ->DataElement(nullptr, &AndroidSplashscreens::m_landscapeSplashscreens)
+                    ->DataElement(nullptr, &AndroidSplashscreens::m_portraitSplashscreens)
                 ;
             }
         }