[lmi] Simplify the census-pasting test?

[Greg Chicares]

'wx_test_paste_census.cpp' extracts sample data for pasting from an
html file that is part of the lmi user manual. Wouldn't it be better
to write those data inline in that source file? I think that would
make the code easier to understand, and the test more robust.

We have routinely used those data for manual testing, but the reason
AFAIK is just that they're conveniently available for manual pasting.
That didactic example was designed mainly to fit on a web page and to
make sense to end users. Some day we might want to make the automated
test more comprehensive, without changing the web page.

If we ever change the example in the user manual, we will of course
test it manually. I don't see any need for 'wx_test' to do that: it's
outside the scope of an automated GUI test.