[lmi] wx_test regression

[Greg Chicares]

With current lmi HEAD, compared to the results here:
  http://lists.nongnu.org/archive/html/lmi/2014-10/msg00069.html
I now see an additional failure, on a test that had passed:

calculation_summary: ERROR (Progress meter maximum count exceeded. [file 
/lmi/src/lmi/progress_meter.cpp, line 98] )

I looked in 'wx_test_calculation_summary.cpp' but I'm not sure
where this arises. My four '[Calc|New]Ill[Full|Summary].txt'
files are a couple days old even though I reran wx_test this
morning, so I guess this line:
    save_illustration_data("New");
is not being reached. That precludes my initial hypothesis that
a progress meter associated with this subsequent operation:
    ui.Char('r', wxMOD_CONTROL | wxMOD_SHIFT); // "Census|Run case"
was failing, so I now guess that the progress-meter problem may
actually be in Skeleton::UpdateViews()...which we did recently
change:

    wxWindowList const& wl = frame_->GetChildren(); // changed to const&
    boost::shared_ptr<progress_meter> meter
        (create_progress_meter
            (wl.size()
            ,"Updating calculation summaries"
            )
        );
    for(wxWindowList::const_iterator i = wl.begin(); i != wl.end(); ++i)
        {
        wxDocMDIChildFrame const* c = dynamic_cast<wxDocMDIChildFrame*>(*i);
        if(c)

But I don't see how making the wxWindowList a const& would
change its size. Somewhere very recently we talked about using
a wx weak pointer for some MDI class, but I didn't apply that.
Any ideas?