fix current measurement by i(xxx) in B sources: first step,

allow spaces before 'i(' token.
Current measurement for devices in series connection
is still not possible.

src/frontend/inpcom.c

@@ -6728,7 +6728,7 @@ inp_meas_current(struct card *deck)
             /* we have found it, but not (in error) at the beginning of the line */
             if (s && s > v) {
                 /* '{' if at beginning of expression, '=' possible in B-line */
-                if (is_arith_char(s[-1]) || s[-1] == '{' || s[-1] == '=') {
+                if (is_arith_char(s[-1]) || s[-1] == '{' || s[-1] == '=' || isspace_c(s[-1])) {
                     s += 2;
                     if (*s == 'v') {
                         // printf("i(v...) found in\n%s\n not converted!\n\n", curr_line);