Feature request: purely integer version of `outline` algorithm

[fogti]

Summary

https://docs.rs/i_overlay/8.1.0/i_overlay/mesh/outline/offset/trait.OutlineOffset.html is the only outline trait + implementation in iOverlay currently, and it requires floating point inputs/outputs despite working with integers internally. It would be nice if an API could be exposed that allows integer input/outputs.

Motivation

The polygon inflation implementation for integers in polygon_unionfind currently has to round-trip integers to floating point numbers to pass them to i_overlay, which then has to convert them into integers again: https://github.com/mikwielgus/polygon_unionfind/blob/911ba3bcea1c4633746e6e25da2fd9708619d431/src/inflate.rs

This seems wasteful and can introduce rounding errors.

Proposed solution

Refactor the current implementation to expose an analogous integer API to the current floating point API.

Alternatives considered

Keep the current status quo.

Additional context

[NailxSharipov]

Yes, I agree. This part does not match the overall design because it uses floating point operations.
The only reason I used floats was to calculate a unit normal vector.
We can consider this technical debt and rewrite it using only integer math.