some refactoring

example/test/testFmt.cpp

@@ -0,0 +1,12 @@
+#include "testFmt.h"
+
+void fmtTests() {
+  sif::fdebug_t("Hallo\n");
+  sif::fdebug("Hallo\n");
+  sif::finfo_t("Hallo\n");
+  sif::finfo("Hallo\n");
+  sif::fwarning("Hello\n");
+  sif::fwarning_t("Hello\n");
+  sif::ferror("Hello\n");
+  sif::ferror_t("Hello\n");
+}