magicrect 1.0.0

• Initial release.
• magic_rectangle(p, q) constructs a magic rectangle (p, q of equal parity; De Los Reyes et al. 2009 for even orders, Chai-Das-Midha 2013 for odd orders) or a nearly magic rectangle (opposite parity; Chai-Singh-Stufken
  2019. for every order for which one exists.
• rectangle_type(p, q) classifies existence (“magic”, “nearly magic”, “none”).
• verify_rectangle(M) checks the defining properties from first principles.
• Exhaustive test suite over all orders up to 40 x 40.