rbmatroska maintenance

Not sure how much active development is going on with rbmatroska, but I wanted to play around with the code and needed to make the following changes to get it to work:

* Support for ruby versions > 1.8.x
* fixed gen_classes_from_libmatroska, which no longer could parse the modern libmatroska cpp files
* Synchronized baseclasses, updated tools to use new class names

Feel free to merge these changes into the main repo, if you find them agreeable.