Make it possible to void the last pomodoro

[PVince81]

When you were disturbed but didn't notice that you left the pomodoro finish, it would be good to get a popup or notification where you can choose whether to mark the pomodoro as complete or void it.

[PVince81]

Actually best would be to have a dialog at the end of the pomodoro, with the following choices:

1. "Take break": this will trigger the break timer
2. "Skip break": skips break
3. "Void": cancels the last pomodoro, in case the user was disturbed