Maurits/add testing

[mwakok]

This PR contains the following updates:

• I have created a /tests folder in the repository with a number of tests. The naming convention for the tests are to prefix “test_” to the scriptname that is being tested. In general, Matlab will recognize any scripts that are prefixed or suffixed with the string “test” as tests. closes Write test scripts #18
• You can run the tests with the script run_tests.m in the folder /mitc. This will find and run all tests in the /tests folder. The test results and the coverage report are stored in the folder /tests/Reports. closes Explore implementation of a testing environment  #44
• The tests are currently not complete, but the pipeline is modular and easily extendible. For now, I have mainly written unit tests, i.e. only testing specific functions, and not yet integration tests, i.e. testing whole features.
• Matlab also has a framework to test apps. I have created a first simple test for this.
• While writing the tests, I have also updated the docstrings of the functions that are tested. In progress to complete Document the API's #55 and Add docstrings to each function #56.
• I have created a Continuous Integration pipeline with Travis. This ensures that each time we push our local repo to GitHub, Travis will deploy a server to run and verify all the tests. I will check whether we can also do this with GitHub Actions (see Enable Continuous Integration #57).

@omarkamouh Have a look at the implementation and let me know if you can run run_tests.m successfully. I am happy to setup a meeting to go through the changes and how to use them. I think that we should make sure that any changes we make to the code from now on become part of the testing pipeline.