How to make a release.

Bump the relevant version numbers:
- Oasis
- CHANGES
sh dist.sh. It creates a tag and a branch numbered by the version.
Push only the tag and not the branch. You obtain a tag with no branch.
Let github create a tarball.
Delete the local branch.
In ocsigen.org-data, copy tyxml/dev to the new version number.
Add the new version in the download page.
Publish on opam.