Use correct separator for "OR" condition in RSS rules

Although RSS rules were correctly parsed, the wrong separator for the
"OR" condition was used to re-generate the string of the rule displayed
in the preferences.

Closes #2205.

src/rss/rssdownloadrule.cpp

@@ -156,7 +156,7 @@ QVariantHash RssDownloadRule::toVariantHash() const
   QVariantHash hash;
   hash["name"] = m_name;
   hash["must_contain"] = m_mustContain.join(" ");
-  hash["must_not_contain"] = m_mustNotContain.join(" ");
+  hash["must_not_contain"] = m_mustNotContain.join("|");
   hash["save_path"] = m_savePath;
   hash["affected_feeds"] = m_rssFeeds;
   hash["enabled"] = m_enabled;

src/rss/rssdownloadrule.h

@@ -62,7 +62,7 @@ public:
   inline bool isEnabled() const { return m_enabled; }
   inline void setEnabled(bool enable) { m_enabled = enable; }
   inline QString mustContain() const { return m_mustContain.join(" "); }
-  inline QString mustNotContain() const { return m_mustNotContain.join(" "); }
+  inline QString mustNotContain() const { return m_mustNotContain.join("|"); }
   inline bool useRegex() const { return m_useRegex; }
   inline void setUseRegex(bool enabled) { m_useRegex = enabled; }
   inline QString episodeFilter() const { return m_episodeFilter; }