Increase and track coverage

[nuclearGoblin]

Does your pull request resolve or partially resolve an issue? Yes, fully.

If Yes, which issue? Resolves #49, #37, and #44.

Does your pull request implement code improvements? Yes.

• Examples in documentation are now present in tests/bin and can be optionally built with make tests.
• The example notebook example-usecase/Yields_and_Resolutions.ipynb now creates plots for 4 elements (if the user creates the additional three files - instructions provided in notebook).
• Makefile and tests now handle coverage.
• Updates documentation with coverage badge.
• Added various other minor tests to the CI to increase coverage.

Does your pull request implement any breaking changes? Yes/Unsure.

If breaking changes are implemented, please describe: The example notebook example-usecase/Yields_and_Resolutions.ipynb will still provide at least the output it provided before. However, in order to run it fully with no errors, the user must now use the main realizeCascades program.

Testing:
This pull request: [X] Alters the existing CI in some way. [X] Adds a new step to the CI. [ ] Does not introduce any features that the CI could not already test. [ ] Is not accompanied by necessary CI changes due to some limitation described below. (Please also describe how new features can be manually tested.)

[codecov-commenter]

Codecov Report

:exclamation: No coverage uploaded for pull request base (develop@7e72edf). Click here to learn what that means. The diff coverage is n/a.

@@            Coverage Diff             @@
##             develop      #69   +/-   ##
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  Coverage           ?   81.80%           
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  Files              ?       12           
  Lines              ?     1253           
  Branches           ?        0           
==========================================
  Hits               ?     1025           
  Misses             ?      228           
  Partials           ?        0           

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[nuclearGoblin]

We will need to remember to change the default branch for Codecov to develop once the merge is complete!