cmake: make opencv required :(

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
sprinkle const

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
add translation compensation

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
remove kludgy compensation

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
double polling interval for rift, hydra

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>