Tested and improved

OK, I've fixed the code so that it runs now with the following performance.
It takes ~170 seconds to parse a corpus.
Only the verb *disqualify* doesn't get parsed. No exception is visible in the log, but when I try to load that file individually I get a memory error at the point of converting the file object into a string. There are close to 4K lines in that file, so no wonder my laptop runs out of memory. A more powerful machine should be able to handle that, however.
It takes ~ 2.5 seconds to pickle a parsed corpus and ~7-8 seconds to load a pickled parsed corpus.

To-Do still:
- [ ] I was thinking of turning some to the methods in the VALEXCorpusReader class into class methods as opposed to instance methods. This would allow the user to load individual verb files without having to parse a whole corpus. What do you think about that?

- [ ] Doc-strings need to be created...

- [ ] We may want to start thinking about parsing this stuff further. I have a lisp repl script lying around somewhere, we could use that as a base for writing a small (and fast!) parser for the expressions because it's basically the same principle of nested parentheses. Or we can use PLY, I'm down for learning how that works too!