fix bug #229 `Node name "n" is sometimes toxic'

Error: too few nodes for MOS or CPL:
m6 1 n 2 vss nch.3 l=4.3e-07 ...

http://sourceforge.net/p/ngspice/bugs/229/

src/frontend/subckt.c

@@ -1472,14 +1472,16 @@ gettrans(const char *name, const char *name_end)
 static bool
 model_bin_match(char *token, char *model_name)
 {
-    char *dot_char;
+    /* find last dot in model_name */
+    char *dot_char = strrchr(model_name, '.');
     bool  flag = FALSE;
-    /* continue evaluation if toeken is part of model_name */
-    if (strncmp(model_name, token, strlen(token)) == 0) {
-        /* find last dot in model_name */
-        if ((dot_char = strrchr(model_name, '.')) != NULL) {
+    /* check if token equals the substring before last dot in model_name */
+    if (dot_char) {
+        char *mtoken = copy_substring(model_name, dot_char);
+        if (cieq(mtoken, token)) {
             flag = TRUE;
             dot_char++;
+            /* check if model_name has binning info (trailing digit(s)) */
             while (*dot_char != '\0') {
                 if (!isdigit(*dot_char)) {
                     flag = FALSE;
@@ -1488,6 +1490,7 @@ model_bin_match(char *token, char *model_name)
                 dot_char++;
             }
         }
+        tfree(mtoken);
     }
     return flag;
 }