refs #91 & #124 doxygen fixes, style/comment changes, typos, and override / nullptr keywords

Remark: Doxygen <70 warnings

src/blackcore/network.h

@@ -117,6 +117,12 @@ namespace BlackCore
          */
         virtual bool isConnected() const = 0;
 
+    signals:
+        /*!
+         * \brief Connection has been terminated
+         */
+        void terminate();
+
     public slots:
         ////////////////////////////////////////////////////////////////
         //! \name Network slots
@@ -398,6 +404,7 @@ namespace BlackCore
 
         /*!
          * We received a reply to one of our queries.
+         * \param callsign capabilities for this callsign
          * \param flags A combination of capabilities flags.
          * \sa sendCapabilitiesQuery
          */