'success returns the GSL_SUCCESS code, required for many callback
definitions.  Introduced macros vref and mref (setfable) to get
components of GSL vector doubles and matrix doubles directly from the
pointers.


git-svn-id: svn+ssh://pop/opt/space/mathematics/gsl/trunk@3265 a3d8a0fb-c1db-0310-ace7-a616afeb9e30