Remove set of unused variables.

Add a new matching rule \m that behaves similar to lua %b, it matches a balanced open and close characters ex:
\m() <- will match a balanced pair of ( and )
\m{} <- will match a balanced pair of { and }
See lua %b for more info.
Also include a nut file as example.

samples/regex.nut

@@ -0,0 +1,10 @@
+local ex = regexp("[a-zA-Z]+");
+local string = "123 Test; strlen(str);";
+local res = ex.search(string);
+print(string.slice(res.begin,res.end)); //prints "Test"
+print("\n");
+ex = regexp(@"\m()");
+string = "123 Test; doSomething(str, getTemp(), (a+(b/c)));";
+res = ex.search(string);
+print(string.slice(res.begin,res.end)); //prints "(...)"
+print("\n");