Version 1.6.0

Added the following things:

- Looped pomodoro mode. Arguments "-lp" and "--lpomodoro".
- Setting "pomodoro_long_break". Specifies the long break in minutes.
  This is only used under the looped pomodoro mode.
- Setting "long_break_cmd". Specifies the long break command. This is
  only used under the looped pomodoro mode.
- Updated the file timrc.example to reflect the new change.
- Updated the screenshot.