Add support for Finnish substitutions (gosimple#18)

languages_substitution.go

@@ -24,6 +24,11 @@ var defaultSub = map[rune]string{
 	'―':  "-", // horizontal bar
 }
 
+var fiSub = map[rune]string{
+	'&': "ja",
+	'@': "at",
+}
+
 var nlSub = map[rune]string{
 	'&': "en",
 	'@': "at",

slug.go

@@ -64,6 +64,8 @@ func MakeLang(s string, lang string) (slug string) {
 		slug = SubstituteRune(slug, grSub)
 	case "nl":
 		slug = SubstituteRune(slug, nlSub)
+	case "fi":
+		slug = SubstituteRune(slug, fiSub)
 	default: // fallback to "en" if lang not found
 		slug = SubstituteRune(slug, enSub)
 	}

slug_test.go

@@ -71,6 +71,7 @@ func TestSlugMakeLang(t *testing.T) {
 		{"es", "This & that", "this-y-that"},
 		{"gr", "This & that", "this-kai-that"},
 		{"nl", "This & that", "this-en-that"},
+		{"fi", "This & that", "this-ja-that"},
 		{"test", "This & that", "this-and-that"}, // unknown lang, fallback to "en"
 	}