[CM] s7: change subvector parameter order?

[bil at ccrma.Stanford.EDU]

I'd like to change subvector to be similar to substring:
(subvector vect offset len) rather than the current:
(subvector vect len (offset 0)).  Years ago I thought
the offset wouldn't be all that useful -- live and learn.
After this change, you could still use the old form via:
(define* (subvector vect len (offset 0))
   (#_subvector vect offset len))
Does anyone violently object?