Work on Make runnable without parameters and with -h (#132)

[therealchjones]

• Change to using System.CommandLine instead of homegrown
• change from using directory name strings to DirectoryInfo for program parameters and methods directly using them
• fixed path in launch.json for net5.0
• Removed unnecessary Program members, added Program.Options
• Removed DirectoryInfo error checking from Program.LoadAll and Program.WriteAll in favor of the ones built into System.CommandLine