As requirements have changed - I'm removing tests and dead code
Added test for validity of pattern according to rectangle/square rules.
 This test is still failing - drove the design into a separate
 function to check coordinates forming squares/rectangles
Added test for checking if coordinates form a row - this is a valid
rectangle
Refactoring the boolean tests in the coordinates_indicate function
Added test to check for case where coordinates indicate column
Refactoring the coordinates_indicate function
Added test for rectangle recognition
Refactored so that there is now a specifc is_rectangle test for a set of coordinates
Added test for case where the rectangle is standing