v1.9.1 and v1.9.2: Reminder activation

[Futsch1]

Main focus of the releases v1.9.1 and v1.9.2 was reminder activation. Since v1.9.1, it is possible to define an active period for a reminder. During this period, the reminder will generate notifications. This might be use when tapering off medication or when pills only need to be taken for a certain period of time.

Additionally, the grammar of reminders is now correct when not indicating an amount for a medication and a Russian translation was added.

v1.9.2 fixed a bug introduced with v1.9.1 where the active period was not correctly taken into account when scheduling reminders.