Use meld for merging files with unison

.unison/default.prf

@@ -14,4 +14,5 @@ follow = Path Musique
 
 repeat = watch
 
-merge = Name {*,.*} -> unison-merge-files CURRENT1 CURRENT2 NEW CURRENTARCHOPT
+# merge = Name {*,.*} -> unison-merge-files CURRENT1 CURRENT2 NEW CURRENTARCHOPT
+merge = Name {*,.*} -> meld CURRENT1 CURRENT2