[latexrefman] list update

[Hefferon, James S.]

I did a lot of stuff recently with the list environment, and based on that I've updated the entry.  In particular, it dawned on me that the left edge of the label is at \leftmargin+\itemindent-(\labelsep+\labelwidth).  Probably that is not a relevation to anyone else but I wanted to have the entry say that.

Besides, the spacing parameters belong in the list entry.

And, I feel that a picture in this case is worth a lot of words, so I added one.  I put it the source in the graphics/asy directory.  If someone has a better idea, that'd be great. 

Jim

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... and if I did fall,
  I would fly.  -- Philippe Petit