fix for negative int data

Author: ericoporto

fancy_demo/fancy.asc

@@ -261,7 +261,7 @@ int _get_tag_data(String tag, TagType tag_type)
   int p = tag.IndexOf(":") + 1;
   if (p == 0) return -1;
   String data = tag.Substring(p, tag.Length-p);
-  if (data.Chars[0] >= '0' && data.Chars[0] <= '9') return data.AsInt;
+  if (data.Chars[0] >= '0' && data.Chars[0] <= '9' || data.Chars[0]== '-') return data.AsInt;
   if (_tvdict.Contains(data)) {
     String sval = _tvdict.Get(data);
     return sval.AsInt;