Fixes #385 - source in header isn't a link

The source item in a GEDCOM header isn't a link. It is a block
describing the source software of that particular GEDCOM file.
As such it needs to be treated as an attribute of the header
and not as a link or as a source object.

Change the object factory used when parsing GEDCOM files to
reflect that changed thinking.

gedbrowser-reader/src/main/java/org/schoellerfamily/gedbrowser/reader/AbstractGedObjectFactory.java

@@ -552,7 +552,11 @@ public final GedObject create(final GedObject parent,
             if (parent.getParent() == null) {
                 return new Source(parent, xref);
             } else {
-                return SOURLINK_FACTORY.create(parent, xref, tag, tail);
+                if (tail.contains("@")) {
+                    return SOURLINK_FACTORY.create(parent, xref, tag, tail);
+                } else {
+                    return ATTR_FACTORY.create(parent, xref, tag, tail);
+                }
             }
         }
     }