Added a 14 segment LED example, driven by the HT16K33 (#219)

No fritzing parts available for the device so no diagrams

i2c/ht16k33_i2c/CMakeLists.txt

@@ -0,0 +1,12 @@
+add_executable(ht16k33_i2c
+        ht16k33_i2c.c
+        )
+
+# pull in common dependencies and additional i2c hardware support
+target_link_libraries(ht16k33_i2c pico_stdlib hardware_i2c)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(ht16k33_i2c)
+
+# add url via pico_set_program_url
+example_auto_set_url(ht16k33_i2c)