Added some standard C regex implementation. (0.20.0)

examples/regex_demo.fun

@@ -0,0 +1,38 @@
+#!/usr/bin/env fun
+
+/*
+ * This file is part of the Fun programming language.
+ * https://hanez.org/project/fun/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the Apache-2.0 license.
+ * https://opensource.org/license/apache-2-0
+ *
+ * Added: 2025-10-04
+ */
+
+// Simple demo of Regex stdlib class.
+
+include <regex.fun>
+
+r = Regex()
+
+text = "abc-123-xyz"
+
+// full match (should be 0)
+m1 = r.match(text, "[a-z]+-[0-9]+-[a-z]+$")
+print(m1)
+
+// search
+s1 = r.search(text, "[0-9]+")
+print(s1)
+
+// replace digits with #
+out = r.replace(text, "[0-9]", "#")
+print(out)
+
+/* Expected output:
+1
+{"match": 123, "start": 4, "end": 7, "groups": []}
+abc-###-xyz
+*/