added line, col number support

Signed-off-by: Tim Henderson <tim.tadh@gmail.com>
test backtracking

Signed-off-by: Tim Henderson <tim.tadh@gmail.com>
backtracking with new line

Signed-off-by: Tim Henderson <tim.tadh@gmail.com>
final fixes and tests for line, col tracking

Signed-off-by: Tim Henderson <tim.tadh@gmail.com>