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>

CMakeLists.txt

@@ -369,6 +369,8 @@ add_library(${PROJECT_NAME}
     src/bacnet/get_alarm_sum.h
     src/bacnet/getevent.c
     src/bacnet/getevent.h
+    src/bacnet/hostnport.c
+    src/bacnet/hostnport.h
     src/bacnet/iam.c
     src/bacnet/iam.h
     src/bacnet/ihave.c