of the d_cosim codemodel, using libvvp, the simulation runtime of
Icarus Verilog. This complements the existing method using Verilator.
The new source code is built into two binary shared libraries,
ivlng.so (or .DLL) and ivlng.vpi that are loaded during simulation.
During installation into C:\Spice.... a spinit
from spinit_all is copied, having relative paths to the
code models.
A local spinit (needed for the running the local debugger)
is copied from either spinitd or spinitd64, referencing
the code models stored in C:\Spiced..\lib\ngspice by
setting the absolute path.