[boost] very simple implementation of Andrei Alexandrescu's ScopeGuard idiom

https://github.com/RSATom/finally_execute/blob/master/finally_execute.h based on http://www.drdobbs.com/cpp/generic-change-the-way-you-write-excepti/18440375... I know about http://sourceforge.net/projects/loki-lib/ but with boost::bind this can be much simpler: https://github.com/RSATom/finally_execute/blob/master/README I've used this in many of my projects, and found it very usefull.... don't understand, why this simple solution does not contributed already to Boost by someone else... :)