some preliminary work for email notification of likes - potentially destabilising so disabled until after next release

boot.php

@@ -403,6 +403,7 @@ define ( 'NOTIFY_PROFILE',  0x0040 );
 define ( 'NOTIFY_TAGSELF',  0x0080 );
 define ( 'NOTIFY_TAGSHARE', 0x0100 );
 define ( 'NOTIFY_POKE',     0x0200 );
+define ( 'NOTIFY_LIKE',     0x0400 );
 
 define ( 'NOTIFY_SYSTEM',   0x8000 );