Number combinations that don't make sense should throw exception

[pandoman]

When you process a string of "numeric" text, w2n returns an incorrect value rather than throw an exception. For example, the string "ten thirty" (imho) should throw an exception because nobody (in the English speaking world) specifies a number using those words. This would be useful when processing a string that, for example, includes time and "ten thirty" should be considered two separate numbers.