added stock bitmap handling and support for it in the demo script

src/Makefile

@@ -4,7 +4,7 @@ SPLASHSCREEN=splash-vmwcblk.png
 
 OBJS=main.o sysinput.o ep_init.o ep_upiwin.o ep_backlight.o ep_msg.o ep_graphics.o ep_devctxt.o ep_bitmap.o \
      ep_upiwin_tmp.o ep_util.o fbinit.o rect.o gfxobj.o devctxt.o dc_screen.o fontengine.o \
-	 bitmap.o fbprimitive.o log.o gpio.o msg_queue.o time_func.o config.o \
+	 bitmap.o stockobj.o fbprimitive.o log.o gpio.o msg_queue.o time_func.o config.o \
 	 i_freehand.o i_line.o i_rect.o i_fillrect.o splash.o
 LIBS=-lpython3.7m -lcrypt -lfreetype -lbcm2835 -lpthread -ldl -lutil -lm
 CFLAGS=-I/usr/include/python3.7m -I/usr/include/freetype2 -I/usr/include/libpng16 \