As of November 2011 I retook the development of this library therefore I tagged the previous version of the library here. If you are looking for the old library then use the code on that tag.
If you are going to use it in a new project I advice that you use the current master branch. There are many performance improvements in that branch and I'm adding more and more tests to it.
Besides that the library has been refactored to use PHP 5.3 namespaces. The classes have been split into their separate files and so on. The idea is to make the library easier to test.