Add nodes by clicking on a line

[shiruken1]

What does this PR do?

Submitted an application and found out about your FOSS. Neat stuff! Was playing around with the code and noticed I couldn't add a node, which I figured I should fix. Went to open this PR and saw PR#22 if y'all think that one's more thorough I can complete the outstanding requested change, instead. Let me know!

Type of Change

• New feature (non-breaking change that adds functionality)

Testing

• I have tested this change locally
• I have added/updated tests for this change

Test details:
N/A? No tests in the codebase

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in hard-to-understand areas
• My changes generate no new warnings or errors
• I have updated the documentation accordingly (if applicable)

Additional Context

This was a fun way to remember basic trigonometry! :)