This library isn't maintained and doesn't support new Wikidata features. For a more cleaner and recent library written in PHP, please see https://github.com/addwiki/wikibase-api
wikibase-api-php is a beginning of an easy to use library that interact with the Wikidata API.
wikibase-api-php is currently in active development and does not provide a stable API. wikibase-api-php supports phase 1 data, reading and creation of phase 2 claims and edition of main snak of claims.
For example of the use of the libary, see the examples folder.
Feel free to hack on it! All contributions are welcome!