[CM] s7_call_with_location

[bil at ccrma.Stanford.EDU]

> What are the rules RE: s7_call_with_location? does it work with any
> applicable object? conversely, how difficult would it be to implement
> s7_eval_with_location?

Yes, it should work with any applicable object.  To
implement s7_eval_with_location, use the location wrapper
code in s7_call_with_location, substituting s7_eval for
s7_call (and making the function arguments match s7_eval).