Parse invalid XML

[andy128k]

It is not a rare situation to meet broken RSS. I have two examples:

1. Unescaped ampersand: <title>Here & there</title>
2. HTML entities: <title>Text with &laquo;angle quotes&raquo;</title>

Formally these documents are invalid, but practically it could be nice to parse them too.

For example Firefox skips such items but does not discard whole RSS.

Currently this crate discards such inputs.