Version 1.5.0

Made some changes to the way the way pomodoro and interval mode works.
More specifically these things are changed:

- Setting "pomodoro_press_return" is renamed to "press_return".
- Interval mode now waits for user input if "press_return" is on.
- Put wait for input code inside of functions (start_break, start_work).
- Tweaked the output of pomodoro mode.
- Added a cross-platform tip in the README.md file.
- Added a newer screenshot of Tim.