few cleanings to get better compatibility with VC++ 2010
file source: use open_with_path()
d_state: improved error messages
global variable Infile_Path, which contains the
input netlist file path
new callback function cm_get_path, which makes the global
ngspice variable Infile_Path available to XSPICE code models
make use of Infile_Path in function open_with_path.
We may now use the following sequence for a file
search from a code model:
Infile_Path/<infile>
NGSPICE_INPUT_DIR/<infile>, where the path is given by the environmental variable
<infile>, where the path is the current directory