Added more tests

tests/programs/mul.q

@@ -0,0 +1,9 @@
+main() {
+	assert 0 * 0 == 0
+	assert 1 * 1 == 1
+	assert 1 * 2 == 2
+	assert 2 * 1 == 2
+	assert 2 * 2 == 4
+	assert 4 * 2 == 8
+	assert 8 * 2 == 16
+}