Add facades and helpers to simplify usage

[bdelespierre]

Proposed change

$data = [
    [80,55],[86,59],[19,85],[41,47],[57,58],
    [76,22],[94,60],[13,93],[90,48],[52,54],
    [62,46],[88,44],[85,24],[63,14],[51,40],
    [75,31],[86,62],[81,95],[47,22],[43,95],
    [71,19],[17,65],[69,21],[59,60],[59,12],
    [15,22],[49,93],[56,35],[18,20],[39,59],
    [50,15],[81,36],[67,62],[32,15],[75,65],
    [10,47],[75,18],[13,45],[30,62],[95,79],
    [64,11],[92,14],[94,49],[39,13],[60,68],
    [62,10],[74,44],[37,42],[97,60],[47,73],
];

// should auto-detect the arity of the euclidean space
$results = kmeans($data, clusters: 3);

For GPS coordinates

$cities = [
    [48.85889, 2.32004], // Paris
    [45.75781, 4.83201], // Lyon
    [43.29617, 5.36995], // Marseille
];

$results = kmeans_gps($cities, clusters: 1);