v2.2.8

One fix: a school day with a break, reported in #190.

Fixed

• School time with a break reads and writes correctly (#190) - Google stores a school day with a break as two slots on the same day, in no fixed order. The time.<child>_<weekday>_school_time_start|end entities kept the first row they met, so a day could show 14:00-15:00 while the next showed 08:00-13:00, and a day without school time (slots disabled) still showed hours. The start is now the earliest slot's, the end the latest slot's, the slots are listed in a windows attribute (08:00-13:00, 14:00-15:00), and a day whose slots are all disabled reads unknown. Setting the start changes the first slot and setting the end the last one, so the break survives.