Add /on NOTICE_GROUP and /fset NOTICE_GROUP analogous to MSG_GROUP

This hook and format are used for NOTICEs where the destination isn't
a channel and isn't yourself - eg. global targets like $$*.org.  This was
already the case for PRIVMSGs (using the MSG_GROUP hook and format).

Previously these were being routed like a normal NOTICE, and those don't
display the target, so it looked exactly like a private NOTICE to you.

This will also catch server notices sent before you're registered.

include/hook.h

@@ -90,6 +90,7 @@ enum HOOK_TYPES {
 	NICKNAME_LIST,
 	NOTE_LIST,
 	NOTICE_LIST,
+	NOTICE_GROUP_LIST,
 	NOTIFY_LIST,
 	NOTIFY_HEADER_LIST,
 	NOTIFY_SIGNOFF_LIST,