Support merging env into rc.
0.8.150
Support listing subcommands in help output.

If a subcommand specifies an extra portion (eg: <file...>) then it is
included in the synopsis list for the parent command.
0.8.151
Include all subcommands in synopsis.

Not just those with an extra property.
0.8.152
Use command short name.

When listing subcommands in the synopsis.
0.8.153
Update info.cmd when invoking subcommands.
0.8.154
Use public extra() method.
0.8.155