Collecting help issues that have come up multiple times.

Override or disable help option:

• Make auto help optional #242 Make auto help optional
• Hiding auto generated help options? #542 Hiding auto generated help options?
• Don't Show options when there are no options #689 Don't Show options when there are no options
• Override --help? #893 Override --help?
• Prevent/override automatic help generation #1215 Prevent/override automatic help generation
• Add method to get help option description #1370 Add method to get help option description

Struck out items included in Command v6.1.0