Setting this to M_RANGE(-1, 10) meant that you could pass fractional
negative values without it being an error. This is, of course, nonsense.
-1 is the only special negative value with a meaning. Error out if we
get anything else by doing some additional parsing before we send it off
to parse_double which will then restrict the range to 0, 10 with these
changes. Note that this approach requires defval to be there which is
not the most extensible thing in the world. But there's literally only
two OPT_ASPECT type options out of the hundreds we have so not a big
deal. Ideally, this type should be OPT_CHOICE but with underlying
doubles but that's too much effort to implement cleanly.