New demo application: nqueens

This is a new demo for the nqueens based on the X10 version.
If I understood you correctly, wouldn't this pass the same GlobalAddress to potentially `nqBoardSize-1` tasks? Then it would be difficult to know when it is ok to delete the Board object pointed to GlobalAddress (since any of the `nqBoardSize-1` tasks could be using it).

The way it works now is: 1) create a local copy (delegates are used to fetch the remote object) - lines 98-104; 2) create a new object for each new task to be spawned (no delegates needed because the local copy have been already created) - line 123.