inpcom.c, enable current measurement in B-line like

Isup 1 0 1
Rsup 1 0 2
Bsup 2 0 i=i(Isup)
Rb 2 0 1

src/frontend/inpcom.c

@@ -6593,8 +6593,8 @@ inp_meas_current(struct line *deck)
             s = u = strstr(s, "i(");
             /* we have found it, but not (in error) at the beginning of the line */
             if (s && s > v) {
-                /* '{' if at beginning of expression */
-                if (is_arith_char(s[-1]) || s[-1] == '{') {
+                /* '{' if at beginning of expression, '=' possible in B-line */
+                if (is_arith_char(s[-1]) || s[-1] == '{' || s[-1] == '=') {
                     s += 2;
                     if (*s == 'v') {
                         // printf("i(v...) found in\n%s\n not converted!\n\n", curr_line);