ngspice emitted a warning message, but then moved on,
inserting it as a new node with fcn INPtermInsert(). This
of course is totally wrong and leads to memory corruption.
Now there is a new fcn INPtermSearch(), which just checks
if the node is existent. If yes, it will get the value
according to the .ic statement, if not, a warning message
is emitted, and the non-existent node is simply ignored.