Test char to int conversion.

tests/printf_test.aer

@@ -22,6 +22,7 @@ class Program {
 	private void testNumbers() {
 		printf("%%b = '%b'\n", $this->n);
 		printf("%%c = '%c'\n", $this->c);
+		printf("%%d = '%d'\n", $this->c);
 		printf("%%d = '%d'\n", $this->n);
 		printf("%%e = '%e'\n", $this->n);
 		printf("%%u = '%u'\n", $this->n);