make: Global change: Move all public headers to include folder.  Change source to including public headers using #include <ndn-cpp/*>. Split some header files to minimize exposing C .h files.
diff --git a/ndn-cpp/c/data.h b/ndn-cpp/c/data.h
index e085f79..8d14e05 100644
--- a/ndn-cpp/c/data.h
+++ b/ndn-cpp/c/data.h
@@ -7,6 +7,7 @@
 #ifndef NDN_DATA_H
 #define NDN_DATA_H
 
+#include <ndn-cpp/c/data-types.h>
 #include "name.h"
 #include "publisher-public-key-digest.h"
 #include "key.h"
@@ -41,15 +42,6 @@
   ndn_KeyLocator_initialize(&self->keyLocator, keyNameComponents, maxKeyNameComponents);
 }
 
-typedef enum {
-  ndn_ContentType_DATA = 0,
-  ndn_ContentType_ENCR = 1,
-  ndn_ContentType_GONE = 2,
-  ndn_ContentType_KEY =  3,
-  ndn_ContentType_LINK = 4,
-  ndn_ContentType_NACK = 5
-} ndn_ContentType;
-
 /**
  * An ndn_MetaInfo struct holds the meta info which is signed inside the data packet.
  */