Feature request: Add pomodoro, 25 minutes button

[QWxleA]

Having a standard time, for example 1 'pomodoro' would make the app even more useful. It is possible to do by hand, but having a button makes the pomodoro flow better.

The inserted tomato image might not be the best possible version.

As an implementation, there could be just be a true/false setting in gsettings to show the tomato or not, and another one for the pre-set time (25m). People who don't need/want it wouldn't see it.