affiner 0.2.1

• has_intersection() is a generic S3 method which tests whether two objects have an intersection.
• intersection() is a generic S3 method which computes the intersection of two objects.
• is_equivalent() is a generic S3 method which tests whether two objects are "equivalent".
  The is_equivalent() method for angle vectors tests whether two angles are congruent.
  The is_equivalent() method for Point1D, Line2D, Plane3D classes tests whether they are the same point/line/plane after standardization.
• is_parallel() is a generic S3 method which tests whether two objects are "parallel" (e.g. Line2D and Plane3D objects).
• isotoxal_2ngon_inner_radius() computes the inner radius of an isotoxal 2n-gon polygon (#66). star_inner_radius() is an alias.
• If R >= 4.4.0 can now also use crossprod() (in addition to cross_product3d()) to compute the
  vector cross product of two Coord3D objects.
• Can now use ceiling(), floor(), round(), signif(), and trunc() on Coord1D, Coord2D, and Coord3D objects (#63).