Feature/raspberry pi blinkt color objects (#503)

* fixed BACnetXYcolor and BACnetColorCommand encode and decoding and improved unit test coverage. Refactored BACnetXYcolor to/from ascii into lighting module.

* added to the color, color temperature, and lighting output objects a fade/ramp/step engine.  Added color and color command coercion into the channel object and enabled color temperature object coercion.  Added CreateObject and DeleteObject service handling to the color, color temperature, lighting output, and channel objects.

* added blinkt demo app for Raspberry Pi [WIP]

* updated gitignore to simplify handling of apps folder contents

* fixed piface demo build

* added RaspiOS to pipeline for piface and blinkt! demo builds

* added device object timer function for child object types into example Device object.  Refactored device object to increment database revision for create or delete object services.   Refactored example app/server to use mstimer library and device child object timers.

---------

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

apps/blinkt/Makefile

@@ -0,0 +1,56 @@
+###############################################################################
+# Makefile for Project - BACnet Blinkt!
+# sudo apt install libpigpio-dev libpigpiod-if-dev pigpiod
+###############################################################################
+
+## General Flags
+TARGET = bacblinkt
+# BACnet objects that are used with this app
+BACNET_OBJECT_DIR = $(BACNET_SRC_DIR)/bacnet/basic/object
+SRC = main.c \
+	blinkt.c \
+	device.c \
+	$(BACNET_OBJECT_DIR)/netport.c \
+	$(BACNET_OBJECT_DIR)/channel.c \
+	$(BACNET_OBJECT_DIR)/color_object.c \
+	$(BACNET_OBJECT_DIR)/color_temperature.c \
+	$(BACNET_OBJECT_DIR)/lc.c \
+	$(BACNET_OBJECT_DIR)/lo.c
+
+CFLAGS += -DMAX_TSM_TRANSACTIONS=1
+
+# TARGET_EXT is defined in apps/Makefile as .exe or nothing
+TARGET_BIN = ${TARGET}$(TARGET_EXT)
+
+# note: link to pigpio daemon so that our app can run without root
+# start pigio daemon with the command 'sudo pigpiod'
+LD_PIGPIO = -Wl,-pthread,-lpigpiod_if2
+LFLAGS += $(LD_PIGPIO)
+
+OBJS += ${SRC:.c=.o}
+
+all: ${BACNET_LIB_TARGET} Makefile ${TARGET_BIN}
+
+${TARGET_BIN}: ${OBJS} Makefile ${BACNET_LIB_TARGET}
+	${CC} ${PFLAGS} ${OBJS} ${LFLAGS} -o $@
+	size $@
+	cp $@ ../../bin
+
+${BACNET_LIB_TARGET}:
+	( cd ${BACNET_LIB_DIR} ; $(MAKE) clean ; $(MAKE) -s )
+
+.c.o:
+	${CC} -c ${CFLAGS} $*.c -o $@
+
+.PHONY: depend
+depend:
+	rm -f .depend
+	${CC} -MM ${CFLAGS} *.c >> .depend
+
+.PHONY: clean
+clean:
+	rm -f core ${TARGET_BIN} ${OBJS} $(TARGET).map ${BACNET_LIB_TARGET}
+
+.PHONY: include
+include: .depend
+