Use src layout to fix editable install with pip

[mauritsvanrees]

See plone/meta#172

This uses a clone of the plone.app.uuid src-layout branch to test that two such packages together work. Seems fine locally.

[mister-roboto]

@mauritsvanrees thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!

[mauritsvanrees]

Replaced by PR #385, although the current PR would still be fine on top of that.

[thet]

This would mess up the GitHub history or at least make it more difficult to browse through the history.
But if it fixes problems playing together with standard tools, I'm fine with that. We probably would want do that for all Plone packages and within an coordinated effort.

[jensens]

I think this one is outdated. @mauritsvanrees ok to close?

[mauritsvanrees]

Yes, we can close. This is something to pick up again for Plone 7 when moving to native namespaces.