changed the modules to use the new BACNet string types.

Modified the device object to handle having the string properties changed via WriteProperty service.
Updated the unit tests.
Updated the demo objects.

bacnet-stack/ao.c

@@ -152,6 +152,7 @@ int Analog_Output_Encode_Property_APDU(
   int len = 0;
   int apdu_len = 0; // return value
   BACNET_BIT_STRING bit_string;
+  BACNET_CHARACTER_STRING char_string;
   char text_string[32] = {""};
   float real_value = 1.414;
   unsigned object_index = 0;
@@ -168,7 +169,9 @@ int Analog_Output_Encode_Property_APDU(
     case PROP_DESCRIPTION:
       // note: the object name must be unique within this device
       sprintf(text_string,"ANALOG OUTPUT %u",object_instance);
-      apdu_len = encode_tagged_character_string(&apdu[0], text_string);
+      characterstring_init_ansi(&char_string, text_string);
+      apdu_len = encode_tagged_character_string(&apdu[0],
+          &char_string);
       break;
     case PROP_OBJECT_TYPE:
       apdu_len = encode_tagged_enumerated(&apdu[0], OBJECT_ANALOG_OUTPUT);