test/web-client/html-form/guessing-labels.php: Reorder test cases a little bit (most general test at the top).
test/web-client/html-form/guessing-labels.php: Add missing require statement and 'use' clause.
src/web-client/html-form.php: Formatting changes (automatically done by IDE).
src/web-client/html-form.php: Tweak label-guessing algorithm for radio-button field-set a bit, making it a little less likely to make a bad guess in the case where the substring of one (particular) button's label includes the label of another button (e.g., one button uses text "subscribe" and a subsequent uses "do not subscribe").