Hello.
As far I know, there is no software like that and I think that almost everybody is using one of this two aproachs
1) Free space Green's function for 3D problems if computing current distributions (eg. MoM)
2) Spectral or spatial Green's functions for boxed/open multilayer structures (2.5D)
Well, you can even use free space Green's functions to analize multilayer structures using Lindell's EIT
(only for dyadic fanatics)
Free tools for computing spatial microstrip and slotline Green's functions
"Sommerfeld; A FORTRAN library for computing Sommerfeld integrals", E. Jimenez, F. Cabrera, J.G. Cuevas, IEEE AP Symposium, Baltimore, USA, 1996
The interactive e-book that eirp has pointed out today. Thanks, boss