Singleton Example - MetaTrader 5용 expert

I was working on an EA and identified that an object should never have more than one copy. Most EA's never get large enough for it to actually matter that a singleton is used, but I like the clarity in the code for the object's type.  This is just an update to a years earlier post of this for MQ4; it may be getting to be time to convert everything to MQ5.
The code follows closely the tutorial at http://www.yolinux.com/TUTORIALS/C++Singleton.html