Enhance probe's help request with -brief and -control_arg

[Gary Dixon]

The new verify_info command found many problems in probe.info (a multi-block info segment documenting the probe command and all of its subsystem requests). These have been corrected in a revision of probe.info.

While the revision changes content in only a few cases, resolving the issues found by verify_info required adding Arguments, Control arguments, and List of XXX requests sections to many requests to resolve those issues.

With this improved formatting for the data, and the improved parsing provided by the new help_ facility, it is now useful to add controls to probe's help request to help summarize the many request formats, and to selectively display information for those request formats of interest to the user.

help_ supports several control arguments for this purpose.

-brief displays Syntax, plus item names in the Arguments, Control arguments, and List of XXX sections.

-control_arg ITEM_NAME display the full description for items in one of those three sections whose name contains the ITEM_NAME control argument.

[Eric Swenson]

​https://s3.amazonaws.com/eswenson-multics/public/mcrs/MCR10084.pdf