Feature/apdu null length returned (#285)

* Add APDU as NULL to get BACnet type lengths.

* Fix bacapp copy test to succeed

* fix BACnet REAL and DOUBLE decode

* Add unit test for NULL APDU encoding for length

* Add unit tests for bacapp context

* refactor host-n-port to hostnport.c module

* fix BVLC decoder

* additional unit testing for bacapp

* include bacdevobjpropref module in builds

* simplify bacapp snprintf to be able to return length

* adjust compiler for variable-length arrays

* fix bug found by scan-build

Authored-by: Steve Karg <skarg@users.sourceforge.net>

src/bacnet/basic/object/command.c

@@ -279,7 +279,7 @@ int cl_decode_apdu(uint8_t *apdu,
                 &bcl->Value.type.Object_Id.type,
                 &bcl->Value.type.Object_Id.instance);
             break;
-#if defined(BACAPP_LIGHTING_COMMAND)
+#if defined(BACAPP_TYPES_EXTRA)
         case BACNET_APPLICATION_TAG_LIGHTING_COMMAND:
             len = lighting_command_decode(&apdu[dec_len], apdu_len - dec_len,
                 &bcl->Value.type.Lighting_Command);