Pomodoro timer resets on break change

[dhruvmisra]

If the timer is paused and the break value is changed, the timer preview resets to the beginning. Although on resuming, the timer starts from the previous paused value.

The timer should follow either one of the two workflows on break change:

1. Reset completely and start from the beginning
   OR
2. Persist the old value when paused and resume from the same value

Please suggest the required workflow @llaske. Adding a PR to implement the second workflow however if need be, I can change it to the first one.

[llaske]

Hmmm, the second workflow is probably better.

[llaske]

Fixed in #751