Use Omega_h CLI Parser for robustness

[Fuad-HH]

PumiTally/src/physics/degas2/degas2-main.cpp

Lines 422 to 426 in 570b325

	if (argc != 5) {
	throw std::runtime_error(
	"Usage: " + std::string(argv[0]) +
	" <mesh_name> <num_particles> <max iter> <source_distribution>");
	}