add encoder.h and decoder.h
diff --git a/include/FLAC++/all.h b/include/FLAC++/all.h
index d74bc65..02c43b4 100644
--- a/include/FLAC++/all.h
+++ b/include/FLAC++/all.h
@@ -20,6 +20,8 @@
 #ifndef FLACPP__ALL_H
 #define FLACPP__ALL_H
 
+#include "encoder.h"
+#include "decoder.h"
 #include "metadata.h"
 
 #endif