Feature/bacnet discover dnet devices (#583)

* Added an example application to discover devices and their objects and properties on a specific destination network. The application uses a BACnet Discovery FSM module along with the BACnet R/W FSM.  The BACnet Discovery module stores the binary property data in Keylists and includes device object property queries and iterators.

* Added callback from BACnet R/W FSM module for I-Am messages.

* Removed dependency in BACnet R/W FSM module on rpm_ack_decode_service_request() which uses calloc/free value lists.  Created an alternate RPM-ACK to RP-ACK processing function.

* Changed RPM handler to skip over unknown property values

apps/Makefile

@@ -193,7 +193,7 @@ SUBDIRS = lib readprop writeprop readfile writefile reinit server dcc \
 	whohas whois iam ucov scov timesync epics readpropm readrange \
 	writepropm uptransfer getevent uevent abort error event ack-alarm \
 	server-client add-list-element remove-list-element create-object \
-	delete-object apdu
+	delete-object server-discover apdu
 
 ifeq (${BACDL_DEFINE},-DBACDL_BIP=1)
 	SUBDIRS += whoisrouter iamrouter initrouter whatisnetnum netnumis
@@ -374,6 +374,10 @@ server: $(BACNET_LIB_TARGET)
 server-client: $(BACNET_LIB_TARGET)
 	$(MAKE) -B -C $@
 
+.PHONY: server-discover
+server-discover: $(BACNET_LIB_TARGET)
+	$(MAKE) -B -C $@
+
 .PHONY: timesync
 timesync: $(BACNET_LIB_TARGET)
 	$(MAKE) -B -C $@