New demo application: nqueens

This is a new demo for the nqueens based on the X10 version.
The problem with symmetric addresses in this example is that I will have to pass the addresses of nqSolutions and nqBoardSize to nqSearch().

I am also experimenting with getting rid of the STL vector<int> and use a standard C++ array. The idea then is to use Grappa memcpy() instead of a loop spawning  delegates (see lines 71-73), hopefully improving performance?!?