Add progress bars/tqdm-ify filters and other dataset operations

[mattwthompson]

When working with large datasets, QCSubmit is asked to do quick operations on many molecules at once. Sometimes these complete quickly, but often they take several minutes to complete. As a user, when my interpreter hangs, I have no idea if it's a few minutes or hours away from finishing, or if it's stuck in a loop somewhere. Without some feedback from QCSubmit, I'm stuck waiting and hoping.

Two places this could be useful are

• Retrieving datasets. I ran through the examples in the docs again and, even though the datasets are not exorbitant, the smallest one took a while to grab and I didn't have the patience to wait for the larger one. If I was a novice user this would turn me off to the program altogether, either thinking the software or data are broken or I somehow made a mistake copy-pasting code.
• Applying filters. Some of the filters are (unavoidably) slow when multiplied out by tens or hundreds of thousands of molecules, and as a user I might want to take advantage of QCSubmit's ability to chain several filters together. If I'm experimenting with different combinations of settings and something's taking a while, it'd be nice to know which one is the cause.