Fixing #62 - Multithreaded test not working

I've made the mutlithreaded tests work again by removing the locks
around calls to external code, I have tested with all the repos I found
for Google Code Issue 249 and they now pass or fail with
OutOfMemoryExceptions has expected.  I've added a test to ensure
multithreading works.  I have not found a test that reliably checks
decent locking of the collections (without the mentioned out of memory
problem, or taking a long time to run).
Merge pull request #68 from MatKubicki/master

Fixing #62 - Multithreaded test not working