Add free to String, update hello_world_harder

examples/hello_world_harder.reid

@@ -1,23 +1,16 @@
 import std::print;
-import std::from_str;
-import std::set_char;
-import std::free_string;
 import std::String;
 
-
 fn main() {
     let mut test = String::from("hello");
 
-    test.push(String::from(" world"));
-
-    test.add_char('!');
-    test.add_char('\n');
+    test.push(String::from(" world: "));
 
     test.push_num(175);
     
     print(test);
 
-    free_string(&test);
+    test.free();
 
     return;
 }

reid/lib/std.reid

@@ -75,6 +75,10 @@ impl String {
         else if rem == 8 { self.add_char('8'); }
         else if rem == 9 { self.add_char('9'); }
     }
+
+    pub fn free(&self) {
+        free((*self).inner as *u8);
+    }
 }
 
 impl binop (lhs: String) + (rhs: *char) -> String {