Add argument ranges and defaults to command line help text.

[StaticPH]

In the absence of a manpage, it helps to include acceptable value ranges, and maybe even defaults, in the help output of a command. Granted, manually trying outlandish arguments does produce error messages which indicate ranges where relevant, but I see no reason for these to be mutually exclusive. The exact format in which to include this information in the help output can be discussed; this just seemed good enough to me. Ideally, these would be included programmatically, rather than hardcoded into the argument description strings, but I'd prefer to leave that up to the developer(s).