Creating template groups

[Colnup]

Hi!
Thanks for the awesome app. I just have a small issue when using it daily. I am an apprentice, and I need to switch up my schedules every week (between school and work). I can't use the "every few weeks" option since I often have 2 weeks of the same type in a row.

I would love to be able to create a "template group" where you can toggle all the sub-templates on/off. It would make it simpler to switch quickly between work/holidays schedules for example.

I might try to code it myself and creating a PR, but I'm not sure I'll have the time.