Vector2DOps fixes

[thehappycheese]

• I agree to follow the project's code of conduct.
• I added an entry to CHANGES.md if knowledge of this change could be valuable to users.
• ran cargo fmt then cargo fmt --all -- --check
• ran cargo clippy --all-features --all-targets -- -Dwarnings

---

Fixing some derps in my previous PR :)

• Removed Send + Sync from Scalar type; as far as I can tell these constraints are only needed if the trait uses threads. Removing Send+Sync should not prevent a user from using the trait with a Send+Sync type.
• Switched to cmath::hypot for magnitude() for instant gain in robustness, and fixed tests to reflect

[michaelkirk]

Thanks!

bors r+

[bors]

Build succeeded!

The publicly hosted instance of bors-ng is deprecated and will go away soon.

If you want to self-host your own instance, instructions are here.
For more help, visit the forum.

If you want to switch to GitHub's built-in merge queue, visit their help page.

• ci result