Axes.legend attribute bug?

Anyhow, changing all occurrences of self.legend to

    > self._legend in fixes my problem, but perhaps
    > there are subtleties I'm not aware of? If I don't hear
    > any objections, I'll commit these changes in a day or two.


Yesterday I was writing the section of the users guide in which I
described the Artist containment hierarchy (Figure contains Axes which
contain lines, legends, etc...) and decided it would be most useful
for the diagram to have attribute names as well as class types. In
the process, I made all of the Artist attributes "public" by removing
the leading underscore. I tried to check for method name clashes but
clearly missed this one. Most of the attributes are lists and are
plural (lines, patches, tables). But there is only one legend per
axes (we could change this). So the alternatives are: 1) support
multiple legends or 2) easier, just rename it; how about "thelegend"
or "legend_"

I don't think 1) is really necessary because we already support
multiple figure legends, so you can place multiple legends around or
over an axes manually in the rare cases where you need this.