Constant piet_common::kurbo::MAX_EXTREMA

pub const MAX_EXTREMA: usize = 4; // 0x0_000_000_000_000_004usize

The maximum number of extrema that can be reported in the ParamCurveExtrema trait.

This is 4 to support cubic Béziers. If other curves are used, they should be subdivided to limit the number of extrema.