Replace existing autoloader with Composer-supplied

- Move Friendica namespace to `src`
- Move required `ezyang/htmlpurifier` to vendor
- Remove existing static autoloader
- Change boot.php reference to the autoloader

vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/Integer.php

@@ -0,0 +1,91 @@
+<?php
+
+/**
+ * Validates an integer.
+ * @note While this class was modeled off the CSS definition, no currently
+ *       allowed CSS uses this type.  The properties that do are: widows,
+ *       orphans, z-index, counter-increment, counter-reset.  Some of the
+ *       HTML attributes, however, find use for a non-negative version of this.
+ */
+class HTMLPurifier_AttrDef_Integer extends HTMLPurifier_AttrDef
+{
+
+    /**
+     * Whether or not negative values are allowed.
+     * @type bool
+     */
+    protected $negative = true;
+
+    /**
+     * Whether or not zero is allowed.
+     * @type bool
+     */
+    protected $zero = true;
+
+    /**
+     * Whether or not positive values are allowed.
+     * @type bool
+     */
+    protected $positive = true;
+
+    /**
+     * @param $negative Bool indicating whether or not negative values are allowed
+     * @param $zero Bool indicating whether or not zero is allowed
+     * @param $positive Bool indicating whether or not positive values are allowed
+     */
+    public function __construct($negative = true, $zero = true, $positive = true)
+    {
+        $this->negative = $negative;
+        $this->zero = $zero;
+        $this->positive = $positive;
+    }
+
+    /**
+     * @param string $integer
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return bool|string
+     */
+    public function validate($integer, $config, $context)
+    {
+        $integer = $this->parseCDATA($integer);
+        if ($integer === '') {
+            return false;
+        }
+
+        // we could possibly simply typecast it to integer, but there are
+        // certain fringe cases that must not return an integer.
+
+        // clip leading sign
+        if ($this->negative && $integer[0] === '-') {
+            $digits = substr($integer, 1);
+            if ($digits === '0') {
+                $integer = '0';
+            } // rm minus sign for zero
+        } elseif ($this->positive && $integer[0] === '+') {
+            $digits = $integer = substr($integer, 1); // rm unnecessary plus
+        } else {
+            $digits = $integer;
+        }
+
+        // test if it's numeric
+        if (!ctype_digit($digits)) {
+            return false;
+        }
+
+        // perform scope tests
+        if (!$this->zero && $integer == 0) {
+            return false;
+        }
+        if (!$this->positive && $integer > 0) {
+            return false;
+        }
+        if (!$this->negative && $integer < 0) {
+            return false;
+        }
+
+        return $integer;
+    }
+}
+
+// vim: et sw=4 sts=4