Add REQ-REP zmq/nn sockets to FairMQ together with a little example program.
Also includes example of using boost::program_options.
add ROUTER/DEALER/PAIR sockets.
Use boost::program_options for managing command line options of the executables.

Existing scripts in example/Tutorial3/macro have been adjusted to use the new format.
Your own scripts that use fairmq executables have to be updated.
Your own executables are not affected.
Use the `--help` option with any FairMQ executable to find out the available options.