[plt-scheme] SRFI 31 rec and dotted arglist

The previous implementation of SRFI 31 `rec' (presumably the reference
implementation) allowed a dotted argument list for the procedure form.
The current implementation does not.  I was going to submit this as a
bug, but I noticed that the syntax specification in the SRFI requires
that the argument list be a proper list.  Is there a reason to require
this?

--dougo at place.org