Package rect implements rectangles and can determine when rectanges intersect, are contained, and when rectangles lie adjacent
Adjacency detects whether two rectangles, r1, and r2, are adjacent. Adjacency is defined as the sharing of a side
Containment returns whether r2 is contained inside of r1
Intersection determine whether two rectangles, r1 and r2, have one or more intersecting lines and produce a result, Point, identifying the points of intersection
Point is a struct defining a coordinates position on a 2D plane
Rectangle struct defines a plane figure with four straight sides and four right angles, which contains 4 vertixes points, P1 through P4
IsRect determins if the rectangle provided really is a rectangle, which by definition means a plane figure with four straight sides and four right angles.