[FeatureRequest] Improve calendar

[wojtekojtek]

Feature Description / 功能描述
A clear and concise description of what you want to happen. / 请描述你想建议加入的新功能。
Material UI for calendar, more features for calendar to make it look like a calendar app, like events, navbar (in md3 style), maybe to-do list would be great. Also better hiding options in calendar, I think long pressing year is not that hard, it would be better to navigate to year (can be set in settings which one), click day on month (also it would be great to see that option in settings) and then long pressing should work, it's kind of password.

Reason / 理由
Please describe why this feature should be added. / 请描述为什么应该加入这个功能。
I think the calendar doesn't have many features, so it looks weird. Also long pressing on Year is too easy to guess.

Suggest Solution / 实现方案
(Optional) Possible ways to implement this feature / （可选）如果你已想出新功能的实现方案，请在这里写出。

[ermcar]

Another app would also be great, as most phones have a default calendar. An android easter egg, a screensaver, a fidget spinner... Simpler and useless-er the better.