[latexrefman] Latex command line options

[Karl Berry]

latex --help is (intended to be) authoritative. They might also all be
in the web2c.texi manual, but I've probably failed to keep that updated.

I intentionally never tried to describe all the cmdline options in the
man pages. Many of them are too obscure. I think they are too obscure
for latexrefman too. 

    I'm thinking of mentioning nonstopmode, output-directory, and
    shell-escape.

Sounds good. --version seems worthwhile too.

Possibly it would be useful to @verbatiminclude the --help output,
since, well, it's a reference. But I'm not at all sure. Up to you.
--thanks, karl.