Cleanup of (font) resources on destroy.

ui/allg5ui/renderer.go

@@ -98,6 +98,10 @@ func (r *Renderer) Refresh() {
 func (r *Renderer) Destroy() error {
 	r.user.Destroy()
 	r.eq.Destroy()
+	for _, f := range r.ft {
+		f.Destroy()
+	}
+	r.ft = nil
 	r.disp.Destroy()
 	return nil
 }