The “export” downloads of the installer should include these two files
as they are of use to regular developers.
* .editorconfig encourages the use of our standard code format
* .env.example is a helper for new developers
This is useful for keeping standard "composer create-project"
checkouts clean. Unless they use "--keep-vcs", in which case
.gitattributes is (correctly) ignored.
This has the side effect that archive-checkouts can't
run phing or phpunit scripts, but I think that's
acceptable.
