Provide helptext which was sometimes missing; update some of it
to be more accurate (mostly they display something w/no args).
Usage syntax messages have the same EBNF as the User's Guide.
In some cases, *exactly* what the user's guide shows... e.g.
talking about "offset" not "address" for trace_image.
Don't use "&function"; functions are like arrays, their name
is their address.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>