Gradient descent training + Added all dataset + graphs improvements

app/Models/GradientDescentPerceptron.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Models;
+
+class GradientDescentPerceptron extends Perceptron {
+
+    public function __construct(
+        array $synaptic_weights,
+    ) {
+        parent::__construct($synaptic_weights);
+    }
+
+    public function activationFunction(float $weighted_sum): float
+    {
+        return $weighted_sum;
+    }
+
+}