update json_object_new_string_len, json_escape_str (internal). Writer handles \x00 correctly

Added parse_null test. This does not change anything with how the parser handles \u0000 or null characters

This commit is addapted from one by Adomas Paltanavičius <adomas@leanholding.com>



git-svn-id: http://svn.metaparadigm.com/svn/json-c/trunk@63 327403b1-1117-474d-bef2-5cb71233fd97

json_object_private.h

@@ -33,7 +33,10 @@ struct json_object
     int64_t c_int64;
     struct lh_table *c_object;
     struct array_list *c_array;
-    char *c_string;
+    struct {
+        char *str;
+        int len;
+    } c_string;
   } o;
 };