wip: vertical mirroring support #297

Job	Run time
format-check	1m 38s
build (release-v4.4, calibration_helper)	2m 24s
build-arduino (release-v4.4, weather)	3m 17s
build (release-v4.4, demo)	2m 20s
build (release-v4.4, dragon)	2m 21s
build (release-v4.4, grayscale_test)	2m 24s
build (release-v4.4, www-image)	2m 11s
build (release-v5.1, calibration_helper)	2m 32s
build (release-v5.1, demo)	2m 20s
build (release-v5.1, dragon)	2m 28s
build (release-v5.1, grayscale_test)	2m 26s
build (release-v5.1, www-image)	2m 39s
build (release-v5.2, calibration_helper)	2m 32s
build (release-v5.2, demo)	2m 21s
build (release-v5.2, dragon)	2m 29s
build (release-v5.2, grayscale_test)	2m 22s
build (release-v5.2, www-image)	2m 30s
build (release-v5.3, calibration_helper)	2m 28s
build (release-v5.3, demo)	2m 44s
build (release-v5.3, dragon)	2m 36s
build (release-v5.3, grayscale_test)	2m 39s
build (release-v5.3, www-image)	2m 27s
build (release-v5.1, screen_diag)	2m 20s
	56m 28s

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