add point class.
add some basic implementation of point class.
add contract.
also pull in measures namespace.
add test for map.
include enumerable.
implement each on point object.
implement distance_to method that calculates distance between two points.
update type signature for euclidean method.
change distance measures to not use contracts.
add to_s method.
don't make point enumerable. just pass on coords to distance.
Merge branch 'feature/add-point-class' into develop