Fixed glitchy seconds display
Fixed glitchy minutes display
Moved pomodoro duration buttons to app bar.
Created Pomodoro library to hold timer-related code.
Hid stop button after timer stopped.
Dismiss appbar when user selects a timer.
Fixed stop button bugs.
Basic scheduled toast implementation.
Refactored toast implementation.
Cancel toast on stopping or switching timers.
Repositioned timer display.
Fine-tuned snapped display.
Minor selector refactoring.
Eliminated shifting in timer display.