---   PREFERENCE FEATURES   ---

user_id				:	identifier of the user, contains integer values in interval [1 - 22]
userX				:	X in interval [1-22], set to "1" if preference belongs to userX, else it is "0"
time_of_day			:	identifier of time of day period, contains integer values in interval [1-7] 
					as the 24 hour day is divided into 7 intervals
time_of_day_Y			:	Y in interval [1-7], set to "1" if preference is defined for the selected time of day, else it is "0"
sensor_brightness_level		:	identifier of sensed brightness, contains integer values in interval [1-7] 
					as the brightness readings interval [0,255] was divided into 7 intervals, used sensor: PDV-P9203
sensor_brightness_level_Z	:	Z in interval [1-7], set to "1" if preference is defined for the selected sensed brightness, else it is "0"
preference_brightness_level	:	identifier of preferred brightness, contains integer values in interval [1-7] 
					as the possible brightness settings interval [0,255] was divided into 7 intervals
preference_brightness_level_Q	:	Q in interval [1-7]
preference_color		:	identifier of preferred color,
preference_color_W		:	W in interval [1-7], set to "1" if defined preference is for selected color, else it is "0"
					color 1 - red
					color 2 - orange
					color 3 - yellow
					color 4 - white
					color 5 - green
					color 6 - blue
					color 7 - purple