tools: new tool to extracts function names declared in V files

vlib/builtin/array_test.v

@@ -121,6 +121,20 @@ fn test_right() {
 	assert b[1] == 3
 }
 
+fn test_right_with_n_bigger_than_array_size() {
+	a := [1, 2, 3, 4]
+	mut b := a.right(10)
+	assert b.len == 0
+	
+	// also check that the result of a.right
+	// is an array of the same type/element size as a:
+	b << 5
+	b << 6
+	assert b.len == 2
+	assert b[0] == 5
+	assert b[1] == 6
+}
+
 fn test_left() {
 	a := [1, 2, 3]
 	b := a.left(2)