[1.19.0] Add TerkaProject view

* Add ability for interactively explore project when calling `terka show
project` command.
* Simplify the codebase:
  * Add `is_stale`, `is_overdue` and `completion_date` properties to
    Task (and remove their calculation from `printer`)
  * Add `total_time_spent` property to project
  * Make `TerkaTask` view neater, remove not working `Comment` section
  * Add `formatter` module to extract formatting operations

1.13.0

Full Changelog: 1.12.0...1.13.0

1.12.0

Full Changelog: 1.9.0...1.12.0

1.9.0

Full Changelog: 1.8.0...1.9.0

1.8.0

Full Changelog: 1.7.0...1.8.0

1.7.0

• Add support external connectors (currently asana)
• Add status for stories and tasks
• Improve printing of stories, tasks, projects and sprints

[1.2.0] Add support for sprints

• Add sprints (you can create, start, list, show, and done sprint)
• Add story points (you can assign story point to any task in a sprint)