NewProgram creates a new Program with some reasonable defaults for Name, Description, and Version.

GitCommitKey is the key for the program's GitCommit data.

NameKey is the key for the program's name.

VersionKey is the key for the program's Version data.

Program defines the struct for holding information about the program.

Command defines the interface for each command in a program.

ContextKey defines the type for holding keys in the context.