lib/connections: Un-deprecate relaysEnabled (fixes #3074)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3098

lib/model/model.go

@@ -2018,6 +2018,7 @@ func (m *Model) CommitConfiguration(from, to config.Configuration) bool {
 	from.Options.URAccepted = to.Options.URAccepted
 	from.Options.URUniqueID = to.Options.URUniqueID
 	from.Options.ListenAddresses = to.Options.ListenAddresses
+	from.Options.RelaysEnabled = to.Options.RelaysEnabled
 	// All of the other generic options require restart. Or at least they may;
 	// removing this check requires going through those options carefully and
 	// making sure there are individual services that handle them correctly.