Change README default format to Markdown and add it to pyproject.toml automatically

[cauebs]

• Added tests for changed code.
• Updated documentation for changed code.

Closes #280.

The problem right now is that I cannot change the pyproject.toml's structure, which is created here: https://github.com/cauebs/poetry/blob/a8b534811c1e11541673eb426d34ef9b824321d4/poetry/layouts/layout.py#L84-L89

I don't find the current solution very elegant. If I want to optionally add the readme to the default pyproject.toml, we'll end up with four different strings (with license and readme, just readme, just license or neither). I could edit the strings to insert a line in the correct position, but that's ugly as well. This TOML library is becoming very inconvenient. How should I deal with this?

[sdispater]

Just so you know I am currently developing a TOML library which should ease the programmatic creation/modification of the pyproject.toml file.

I'll let you know when it's ready (hopefully it should be this week).

[cauebs]

Awesome. Let me know if you want some help ;)

[sdispater]

@cauebs I merged the PR with the new TOML library (TOML Kit) which should help with interacting with the pyproject.toml file.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[finswimmer]

Close in favor of #1515

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.