Add pear modules, mail and net_smtp via composer (#93)

Add pear modules, mail and net_smtp via composer, remove php 5.6 build due to phpunit 6

lib/composer/vendor/phpunit/php-token-stream/tests/_fixture/class_with_method_named_empty.php

@@ -0,0 +1,7 @@
+<?php
+class class_with_method_named_empty
+{
+    public function empty(): void
+    {
+    }
+}

lib/composer/vendor/phpunit/php-token-stream/tests/_fixture/class_with_multiple_anonymous_classes_and_functions.php

@@ -0,0 +1,26 @@
+<?php
+class class_with_multiple_anonymous_classes_and_functions
+{
+    public function m()
+    {
+        $c = new class {
+            public function n() {
+                return true;
+            }
+        };
+
+        $d = new class {
+            public function o() {
+                return false;
+            }
+        };
+
+        $f = function ($a, $b) {
+            return $a + $b;
+        };
+
+        $g = function ($a, $b) {
+            return $a - $b;
+        };
+    }
+}

lib/composer/vendor/phpunit/php-token-stream/tests/_fixture/php-code-coverage-issue-424.php

@@ -0,0 +1,13 @@
+<?php
+
+class Example
+{
+    public function even($numbers)
+    {
+        $numbers = array_filter($numbers, function($number) {
+            return $number % 2 === 0;
+        });
+
+        return array_merge($numbers);
+    }
+}