The key is in the build-system table, so making this a dash would
improve consistency. On English keyboards, it also avoids needing to
press shift. There seemed to be a consensus on distutils-sig in favour
of this change.
* 517: Remove install_editable hook (Option 1c)
This is the other option for --user editable installs: don't try to
standardise a mechanism. This could always be added back in a later PEP.
Alternative to gh-140
* Add note about removal of editable install