Added tokenizers: Scala3, C, C++, MATLAB

[Harman-Aalto]

-Added Pygments library to requirements
-Pygments library can be used to add even more tokenizers for the future
-Checksum of submitted source code is now calculated by ignoring the injected separator string in the first and last line of the file
-New tokenizers for languages: Scala3, C, C++, MATLAB #30
-Scala tokenizer depends on the outdated library Scalariform #33

Description

What?

Added new tokenizers and update Scala tokenizer. Removed Scalariform.

Why?

These new tokenizers are useful. Scalariform library removed due it being outdated.

How?

Used the Pygments library in Python

Fixes #30
Fixes #33

Testing

Remember to add or update unit tests for new features and changes.

• How to test your changes in A-plus
• How to test accessibility

What type of test did you run?

• Accessibility test using the WAVE extension.
• Django unit tests.
• Selenium tests.
• Other test. (Add a description below)
• Manual testing.

For each tokenizer a few excerise files were created and uploaded into Radar and those submissions were then compared to each other. Checked for 100% similarity with identical files and used other files for less than 100% similarity checking.

Did you test the changes in

• Chrome
• Firefox
• This pull request cannot be tested in the browser.

Think of what is affected by these changes and could become broken

Translation

• Did you modify or add new strings in the user interface? (Read about how to create translation)

Programming style

• Did you follow our style guides?
• Did you use Python type hinting in all functions that you added or edited? (type hints for function parameters and return values)

Have you updated the README or other relevant documentation?

• documents inside the doc directory.
• README.md.
• Aplus Manual.
• Other documentation (mention below which documentation).

Is it Done?

• Reviewer has finished the code review
• After the review, the developer has made changes accordingly
• Customer/Teacher has accepted the implementation of the feature

Clean up your git commit history before submitting the pull request!

[mikaelGusse]

Great stuff! Tried this out and seemed to work ok. During testing noticed that the highlighter is pretty broken sometimes. We should probably fix that quite soon.