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/ActorUtil.cpp

@@ -103,7 +103,7 @@ bool ActorUtil::ResolvePath( RString &sPath, const RString &sName )
 
 Actor* ActorUtil::LoadFromNode( const XNode* pNode, Actor *pParentActor )
 {
-	ASSERT( pNode != NULL );
+	ASSERT( pNode != nullptr );
 
 	// Remove this in favor of using conditionals in Lua. -Chris
 	// There are a number of themes out there that depend on this (including