The big NULL replacement party part 1.

This is meant to be a safer alternative since
NULL can often be 0. Let's not rely on that.

And yes, I know this is a lot of files. This is
a safer thing to do in big commits vs for loops.

src/InputQueue.cpp

@@ -38,7 +38,7 @@ bool InputQueue::WasPressedRecently( GameController c, const GameButton button,
 		if( iep.GameI.button != button )
 			continue;
 
-		if( pIEP != NULL )
+		if( pIEP != nullptr )
 			*pIEP = iep;
 
 		return true;