Add core stack headers into bacdef.h and cleanup includes. (#602)

* Added dependent BACnet stack headers into bacdef.h file.

* Changed bacdef.h and other stack includes in c/h files to have a common pattern.

* Moved bits.h, bytes.h, and bacnet_stack_exports.h under bacnet/basic/sys/ folder.

apps/gateway/main.c

@@ -34,30 +34,31 @@
 #include <string.h>
 #include <signal.h>
 #include <time.h>
-#include "bacnet/config.h"
-#include "gateway.h"
-#include "bacnet/basic/binding/address.h"
+/* BACnet Stack defines - first */
 #include "bacnet/bacdef.h"
-#include "bacnet/basic/services.h"
-#include "bacnet/basic/services.h"
-#include "bacnet/datalink/dlenv.h"
+/* BACnet Stack API */
 #include "bacnet/bacdcode.h"
 #include "bacnet/npdu.h"
 #include "bacnet/apdu.h"
 #include "bacnet/iam.h"
-#include "bacnet/basic/tsm/tsm.h"
-#include "bacnet/basic/object/bacfile.h"
-#include "bacnet/datalink/datalink.h"
 #include "bacnet/dcc.h"
-#include "bacnet/basic/tsm/tsm.h"
-#include "bacnet/basic/object/lc.h"
-#include "bacnet/basic/sys/debug.h"
 #include "bacnet/version.h"
+/* some demo stuff needed */
+#include "bacnet/basic/binding/address.h"
+#include "bacnet/basic/tsm/tsm.h"
+#include "bacnet/basic/services.h"
+#include "bacnet/basic/sys/debug.h"
+#include "bacnet/datalink/datalink.h"
+#include "bacnet/datalink/dlenv.h"
 /* include the device object */
 #include "bacnet/basic/object/device.h"
+#include "bacnet/basic/object/bacfile.h"
+#include "bacnet/basic/object/lc.h"
 #ifdef BACNET_TEST_VMAC
 #include "bacnet/basic/bbmd6/vmac.h"
 #endif
+/* me! */
+#include "gateway.h"
 
 /** @file gateway/main.c  Example virtual gateway application using the BACnet
  * Stack. */