Move headers under the hf directory.

This helps distinguish local headers from the more official headers.

Change-Id: I535c1b44081b9d60ba63666cd1ad514aaaf2c68d
diff --git a/src/memiter.c b/src/memiter.c
index 6dd9d8c..57cf98b 100644
--- a/src/memiter.c
+++ b/src/memiter.c
@@ -1,6 +1,6 @@
-#include "memiter.h"
+#include "hf/memiter.h"
 
-#include "std.h"
+#include "hf/std.h"
 
 /**
  * Initialises the given memory iterator.