Feature request: Provide column number for syntax errors, too

[billdenney]

In the R port for dparser, I wanted to have syntax errors clarified as I was having trouble tracing an issue. I made the following PR there: nlmixr2/dparser-R#13

But, @mattfidler indicated that code was auto-generated from the dparser source. I think that the correct location to make the changes would be here:

dparser/parse.c

Lines 1636 to 1639 in c74f863

	if (after)
	fprintf(stderr, "%s:%d: syntax error after '%s'\n", fn, p->user.loc.line, after);
	else
	fprintf(stderr, "%s:%d: syntax error\n", fn, p->user.loc.line);

But, I'm not really a C programmer, and I wouldn't know how to test what I'm changing, either. So, would it be possible to make the location indicate the line and column?