Merge screen-diag example by @jdoubleu #156

Job	Run time
build-arduino (release-v4.4, weather)	4m 7s
build (release-v4.4, calibration_helper)	2m 25s
build (release-v4.4, demo)	2m 30s
build (release-v4.4, dragon)	3m 47s
build (release-v4.4, grayscale_test)	2m 19s
build (release-v4.4, mpd_status)	3m 20s
build (release-v4.4, terminal)	2m 34s
build (release-v4.4, www-image)	2m 23s
build (release-v4.4, screen_diag)	1m 10s
build (release-v5.1, calibration_helper)	3m 34s
build (release-v5.1, demo)	2m 17s
build (release-v5.1, dragon)	3m 9s
build (release-v5.1, grayscale_test)	3m 8s
build (release-v5.1, mpd_status)	4m 1s
build (release-v5.1, terminal)	2m 28s
build (release-v5.1, www-image)	3m 7s
build (release-v5.1, screen_diag)	3m 10s
build (release-v5.0, screen_diag)	3m 11s
	52m 40s

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