HexToDec: More lenient triggers

This change makes HexToDec also accept queries like these:

    0xff in decimal
    0xff hex to dec
    0xff as base 10
    0xff in base-10
    0xff hex to base10

The new behavior is more consistent with the Base goodie.
Can you add more triggers for things that you know shouldn't fire here? Especially around "in" and "as"