Convert pkg-message to ucl format.

It means the message specifying the rename of the binary mutt to neomutt
will only be shown to people installing neomutt from the first time
and to people upgrading from a version of neomutt which used to have the
binary named mutt

mail/neomutt/Makefile

@@ -2,7 +2,7 @@
 
 PORTNAME=	neomutt
 PORTVERSION=	20180716
-PORTREVISION=	3
+PORTREVISION=	4
 DISTVERSIONPREFIX=	${PORTNAME}-
 CATEGORIES=	mail
 

mail/neomutt/pkg-message

@@ -1 +1,15 @@
+[
+{
+	message: <<EOD
 /!\ Neomutt no longer install binaries named "mutt" but "neomutt" /!\
+EOD,
+	type : install
+},
+{
+	message: <<EOD
+/!\ Neomutt no longer install binaries named "mutt" but "neomutt" /!\
+EOD,
+	type = upgrade,
+	maximum_version = "20171013"
+}
+]