Minor additions

Ok, let's do this...

I can't seem to get hf5py installed, I keep getting an error that some header file is missing, which causes gcc to freak out and the installation to crash.

I've сreated a docstring for the corpus reader. Also, there was apparently a problem loading the pickled corpus, so I had to change one line for that to work.

As for the DependentList class, I tested it out on the verb "zip" and it seems to work fine. I shortened the regular expression, but that was all. Was there some issue you wanted to address with this class or were you just looking to incorporate it more actively into the rest of the parsing?