Migrate to Python 3 only to use functools.lru_cache
Up until this point, this project has been python 2 and 3 compatible. I propose migrating to python 3 to take advantage of a feature (introduced in 3.2) in the functools standard library called lru_cache.
We can decorate one of our higher level mdsplus function calls with lru_cache to allow the caching of data. I'm not sure how big of a cache we want. It could be something we have in a config file somewhere.