Adding unit tests, golden files, and supplemental labels

[esimpsons3ti]

This pull request will introduce the unit tests for the indexing tools.

Fixes #7

Fixes #6

Fixes #5

[esimpsons3ti]

This is now in a state to be actually looked at. The changes also now include new functionality in the current program to do the following:

• Now reads elements file as glob statements
• square brackets are replaced by angled brackets
• Comments within label are now removed automatically
• And more!

Let me know if you have any questions.

[esimpsons3ti]

I have added the new command line argument function, now named --dump-available-elements.

Fixes #8