Warn about bezier curves in path data

[JayFoxRox]

We should avoid bezier curves if possible (for performance and to reduce file complexity).

I believe some of the very straight lines are actually bezier curves, because someone probably accidentally touched a handle.

We should find such cases and if the handles and control points are on the same line (or very close to it), then we should probably warn, so the user can turn it into a straight line.