Draft: Remove spline fit and min length check from plane slice planner

[marip8]

This PR updates the plane slice planner to remove the parametric spline fitting and minimum segment length checks (in favor of using modular tool path modifiers to do these tasks).

[marip8]

TODO

• Create minimum segment length tool path modifier
• Resolve issue with strange generation of tool path directions seen in the image below.

[marrts]

Resolve issue with strange generation of tool path directions seen in the image below.

This is because they are ordered based off the direction that you specify, not necessarily the order that makes the most sense, or the shortest path.