feature/161 - Add duplicate() method to Project (#161)

[psybers]

Description

This PR adds a duplicate() method to the Project model, which will duplicate the project on Taiga when called. This causes Taiga to make a new project using the newly specified name/description/is_private/users, but copying the original project's settings, including color names, priorities, etc. It does not duplicate any user stories or tasks.

References

Fix #161

Checklist

• [X] I have read the contribution guide
• [X] Code lint checked via inv lint
• [X] changes file included (see docs)
• [X] Usage documentation added in case of new features
• [X] Tests added

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (380660e) 96.49% compared to head (df5c3ab) 96.51%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #163 +/- ## ========================================== + Coverage 96.49% 96.51% +0.01% ========================================== Files 8 8 Lines 914 918 +4 Branches 69 69 ========================================== + Hits 882 886 +4 Misses 19 19 Partials 13 13 ``` | [Flag](https://app.codecov.io/gh/nephila/python-taiga/pull/163/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/nephila/python-taiga/pull/163/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila) | `96.51% <100.00%> (+0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila#carryforward-flags-in-the-pull-request-comment) to find out more.

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[coveralls]

coverage: 97.93% (+0.009%) from 97.921% when pulling df5c3abd1b54991b87fdf20f27aef6730d766637 on psybers:feature/161-add-duplicate into 380660ea50439f1b30a2fd3750a4783ef8c179ab on nephila:master.

[protoroto]

@psybers Thank you very much for this! It looks good, I'll have @yakky have a look at it after Christmas to merge and release a new version!

[yakky]

@psybers awesome, thanks a lot :+1: