Display option to hide feed only when category is not already hidden

ui/feed_edit.go

@@ -59,6 +59,7 @@ func (h *handler) showEditFeedPage(w http.ResponseWriter, r *http.Request) {
 		FetchViaProxy:               feed.FetchViaProxy,
 		Disabled:                    feed.Disabled,
 		HideGlobally:                feed.HideGlobally,
+		CategoryHidden:              feed.Category.HideGlobally,
 	}
 
 	sess := session.New(h.store, request.SessionID(r))

ui/form/feed.go

@@ -31,6 +31,7 @@ type FeedForm struct {
 	FetchViaProxy               bool
 	Disabled                    bool
 	HideGlobally                bool
+	CategoryHidden              bool // Category has "hide_globally"
 }
 
 // Merge updates the fields of the given feed.