Add IRCv3 metadata response codes

Add new numeric response codes from IRCv3 draft.

Author: revrsefr

include/numeric.h

@@ -77,6 +77,15 @@ enum
 	RPL_UNLOADEDMODULE = 973,
 	ERR_CANTLOADMODULE = 974,
 	RPL_LOADEDMODULE = 975,
+
+	// From IRCv3 draft/metadata-2.
+	RPL_WHOISKEYVALUE = 760,
+	RPL_KEYVALUE = 761,
+	RPL_KEYNOTSET = 766,
+	RPL_METADATASUBOK = 770,
+	RPL_METADATAUNSUBOK = 771,
+	RPL_METADATASUBS = 772,
+	RPL_METADATASYNCLATER = 774,
 };
 
 namespace Numeric