After upgrading to Sabre VObject 3, new packages are required.
Use git master head from rF.
Dependencies and versions are listed in [[ /diffusion/F/browse/master/composer.json | composer.json ]] and shall be installed as individual php-* packages (T55). Besides `sabre/vobject`, this also includes `monolog/monolog`and `desarrolla2/cache`.
Then use `composer-dist.json` to just build a local autoloader for the freebusy project which is configured to load classes from `/usr/share/php/` and `/usr/share/pear/`.