centroid method
Computes the centroid (centre of mass) of this triangle. This is also the point at which the triangle's three medians intersect (a triangle median is the segment from a vertex of the triangle to the midpoint of the opposite side). The centroid divides each median in a ratio of 2:1.
The centroid always lies within the triangle.
@return the centroid of this triangle
Implementation
Coordinate centroid() {
return centroidStatic(this.p0, this.p1, this.p2);
}