AntennaPod fails to parse the website links for some feeds

When a feed contains links to alternate feeds like in the example below, the last alternate link will override the website link, because the feed parser fails to check the link's MIME-Type.
```xml
<link>http://einschlafen-podcast.de</link>
<atom:link rel="self" type="application/rss+xml" title="Einschlafen Podcast (Einschlafen Podcast (aac))" href="http://einschlafen-podcast.de/feed/aac/" />
<atom:link rel="alternate" type="application/rss+xml" title="Einschlafen Podcast (Einschlafen Podcast)" href="http://einschlafen-podcast.de/feed/mp3/" />
<atom:link rel="alternate" type="application/rss+xml" title="Einschlafen Podcast (Einschlafen Podcast (Opus))" href="http://einschlafen-podcast.de/feed/opus/" />
```