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>

Makefile

@@ -212,6 +212,11 @@ pretty-ports:
 	find ./ports -maxdepth 2 -type f -iname *.h -o -iname *.c -exec \
 	clang-format -i -style=file -fallback-style=none {} \;
 
+.PHONY: pretty-test
+pretty-test:
+	find ./test/bacnet -maxdepth 2 -type f -iname *.h -o -iname *.c -exec \
+	clang-format -i -style=file -fallback-style=none {} \;
+
 CLANG_TIDY_OPTIONS = -fix-errors -checks="readability-braces-around-statements"
 CLANG_TIDY_OPTIONS += -- -Isrc -Iports/linux
 .PHONY: tidy