Created SpaceList type

internal/codegen/codegen.go

@@ -68,8 +68,7 @@ var attribTypes = map[string]AttribTypeInfo{
 		Imports:  []string{"strconv"},
 	},
 	"space list": {
-		Template: listTemplate(" "),
-		Imports:  []string{"strings"},
+		Template: simpleTemplate("...string", "SpaceList(%s).String()"),
 	},
 	"comma list": {
 		Template: listTemplate(","),