func-*.go modules renamed as builtin-*.go.

Also changed and exported some identiefier relatet to the builtin feature

t_module-register_test.go

@@ -12,7 +12,7 @@ func TestIterateModules(t *testing.T) {
 	section := "Module-Register"
 
 	mods := make([]string, 0, 100)
-	IterateModules(func(name, description string, imported bool) bool {
+	IterateBuiltinModules(func(name, description string, imported bool) bool {
 		mods = append(mods, name)
 		return true
 	})