Fix weird line.tsx behaviour

[vezwork]

Thank you so much @gracefh for merging QCLine and PulleyLine into a single component.

This PR fixes a bug/weird-behaviour that comes from QCLine.

Here's the weird behaviour:

Here's after the fix (blue color to show that the line starts and ends and box boundaries and does not go to their centers):

[vezwork]

Tested the diagrams that use Line and they are working in my local storybook!

[joshpoll]

These changes mostly look good to me. I noticed a few discrepancies with the papers in the diagram though:

• The Python tutor state does not match the paper state
• The UIST figure annotation boxes should be rounded with rx={10}
• The Ohm Parser should use 3 + (4 5) instead of 3 + 4 5

There are also some regressions on interactivity and scenegraph debug mode, but those should be fine for now. We will have to fix post deadline.

[gracefh]

I'll work on the example discrepancies! Thanks so much for getting the fix done @vezwork