[CM] Fastest way to copy scheme variables into a shared buffer?

[bil at ccrma.Stanford.EDU]

> any chance we can get more than a single word of data for c objects?

Yes, but I don't see the need.  If the s7_cell space is made available
to the user, I lose any flexibility in using that space later, and
I'll need to add a half-dozen more procedures to the c-object interface:
s7_c_object_value2, 2-value forms for the equality, mark, free, and
the 3 make procedures (in s7.h all the cases where (void *) value 
occurs),
etc.  The value-passing equal, mark and gc cases are informally
deprecated, so I guess they don't count, but it's kind of
unavoidable in the make cases, unless I add s7_c_object_set_value1|2.

Why can't you use a C struct or array, or an s7 vector or list
as the value, and store any number of things through the value field?
And if you need 2, surely you'll soon need 3.