fix handling of implicit and before parens

fix handling of implicit and before parens

Fix an oddity in matching options and preferred content expressions such as
"foo (bar or baz)", which was incorrectly handled as if it were "(foo or
bar) and baz)" rather than the intended "foo and (bar or baz)"

Seemed like a change to consume should be able to handle this case
better, but I was having trouble writing it that way, so instead added
a separate pass that inserts the implicit ands explicitly. Also added
several test cases to make sure versions with and without explicit ands
generate the same.