cfg: rename legacyprotocol to protocol

Since we are also going to use it for experimental new features.

lncfg/protocol_legacy_off.go

@@ -2,21 +2,21 @@
 
 package lncfg
 
-// LegacyProtocol is a struct that we use to be able to test backwards
+// ProtocolOptions is a struct that we use to be able to test backwards
 // compatibility of protocol additions, while defaulting to the latest within
-// lnd.
-type LegacyProtocol struct {
+// lnd, or to enable experimental protocol changes.
+type ProtocolOptions struct {
 }
 
 // LegacyOnion returns true if the old legacy onion format should be used when
 // we're an intermediate or final hop. This controls if we set the
 // TLVOnionPayloadOptional bit or not.
-func (l *LegacyProtocol) LegacyOnion() bool {
+func (l *ProtocolOptions) LegacyOnion() bool {
 	return false
 }
 
-// LegacyOnion returns true if the old commitment format should be used for new
-// funded channels.
-func (l *LegacyProtocol) LegacyCommitment() bool {
+// LegacyCommitment returns true if the old commitment format should be used
+// for new funded channels.
+func (l *ProtocolOptions) LegacyCommitment() bool {
 	return false
 }